Channel Five and Turner Broadcasting have criticised Ofcom's decision on junk food advertising, calling it "draconian" and a "missed opportunity".
However, Channel 4 has called Ofcom's decision a "proportionate response to a complex social issue" but warned it will cause the channel "financial difficulties".
Meanwhile, ITV released a statement in which it refused to criticise the government or even say how the ban would affect it.
Nickelodeon, which also runs Nick Jr and Nick Toons, said today's announcement was "very tough" for dedicated children's channels.
And music channels reacted with astonishment to Ofcom's decision to extend the ban to include 10- to 15-year-olds.
The future of UK children's programmes on commercial television now looks "bleak", according to the Five chief executive, Jane Lighting.
Ms Lighting re-iterated her channel's commitment to well-regarded pre-school brand Milkshake! but said the future looks difficult for Five.
She said: "This is a tough decision and we are disappointed it is even more draconian than the stringent measures that Ofcom originally proposed.
"Five has a continuing commitment to broadcasting children's programmes both for our Milkshake! pre-school audience and for older children."
She added: "However, these restrictions will deny us substantial revenue and make the economics of producing children's programmes a lot more difficult in the future. "The long-term future of UK-produced children's programming outside the BBC is bleak."
Five's children's output includes such favourites as Make Way for Noddy and Thomas & Friends.
Its non-children's shows that may be affected include Australian soap Home and Away and Make Me a Supermodel.
Turner Broadcasting, which owns kids channels Cartoon Network, Toonami and Boomerang, has also criticised Ofcom's proposals, saying its plan to use characters like Scooby-Doo to promote healthy eating would now be barred.
The company described the junk food ban as a "missed opportunity for a creative and considered solution" to the problem of childhood obesity and said it had been looking at ways it could use its cartoon characters.
"Turner, like other media companies, had been looking at ways in which we could harness our characters, such as Scooby-Doo and Dexter, for the power of good, aligning them with the promotion of healthier food products, such as water, fruit and vegetables," the Turner senior vice-president, Dee Forbes, said.
"Sadly, the new restrictions will deny us this potentially exciting route to complement other forms of health promotion."
Ms Forbes said Turner had consistently argued that restrictions on advertising alone were "not the answer".
"We believe that parents are looking for responsible broadcasters to work with them to make healthy foods, such as fruit and vegetables more attractive to kids," she said.
"With this objective, Turner created the widely acclaimed Elfy Foods series, both in the spirit of good faith and to show that we could reach kids with a positive message in a non-patronising, fun yet educational way.
"Turner Broadcasting is concerned that Ofcom's failure to share our ambition and vision for a regulatory solution incorporating both reasonable advertising restrictions as well as incentives to invest in creative promotion of healthier lifestyles means that the positive power of TV will not now be harnessed to support the work of schools and parents.
"The new restrictions will also undermine the breadth of investment in quality original UK animation and kids programming more generally, an area of the UK's creative economy which is already overly dependent upon the commissioning dominance of the BBC."
However, Channel 4 has called Ofcom's decision a "proportionate response to a complex social issue".
But it has warned it will lead to more financial difficulties for the channel.
The broadcaster - which is currently being reviewed by Ofcom about its funding and remit - recognised that Ofcom had tried to find a "third way" that would appease the anti-junk food lobby and television companies.
A Channel 4 spokeswoman said: "With this proposal we believe Ofcom has tried to strike a balance between reducing children's exposure to [high fat salt and sugar foods] advertising and ensuring the UK's commercial broadcasters have the funding necessary to produce a range of high-quality public service output.
"We believe this is a proportionate response to a complex social issue, although any measure that puts further pressure on TV advertising revenues at a time when the market is experiencing a significant downturn will add to the financial difficulties that Channel 4 is facing".
Programmes expected to affected on Channel 4 include US comedy Friends, The Simpsons, teen soap Hollyoaks and T4. Its music content - such as exclusive previews of videos - could also be under threat.
Its shows specifically aimed at young children are limited and include Cubeez and The Hoobs.
Nickelodeon, which also runs Nick Jr and Nick Toons, said today's announcement was "very tough" for dedicated children's channels.
However, the managing director, David Lynn, did welcome Ofcom's differentiation in foods which will allow it to still screen adverts for food products such as smoothies.
"There is no doubt that Ofcom's announcement today is very tough for the dedicated children's channels," he said.
"Our concern is that this will have a significant effect on investment in original programming across the industry.
"We see this as a missed opportunity to do more to harness the ability of channels like Nickelodeon to use their popularity to positively influence and educate children.
"However, we do welcome the differentiation of foods which will allow us to continue to advertise healthy food ranges such as Innocent and Ella's Kitchen on our channels. That is what we need to focus on now."
ITV released a statement in which it refused to criticise the government or even say how the ban would affect it.
"ITV is a responsible broadcaster and we recognise public concern over this issue," a spokesman said.
"Today's proposals will have a clear impact on the number of HFSS food ads seen by children. Ofcom has gone even further than its original proposals in restricting advertising in programmes of particular appeal to all children across the whole of the schedule.
"With these proposals, commercial television will be going further than any other medium to tackle head-on concerns over the impact of food advertising on children's health and nutrition."
ITV breakfast franchise GMTV went further, saying the ban would spell the end of food advertising in its children's programming.
The restrictions will mean the end of virtually all food advertising in GMTV's children's schedule," a spokeswoman said.
"Ofcom's restrictions will have an impact on the money available to fund UK children's programmes across all channels.
"The restrictions are much as we expected, the only difference being the extension of 16 as opposed to 9-year-olds, but this extension will not have any impact on GMTV.
"We will attempt to substitute this category of advertising in our children's programmes. Our weekday programme will be unaffected by the restrictions as there are only a tiny proportion of under-16s' watching."
Music channels reacted with astonishment to Ofcom's decision to extend the ban to include 10- to 15-year-olds.
Michiel Bakker, the executive vice-president and managing director for MTV Networks UK & Ireland said: "Ofcom's surprising and unexpected decision to extend the ban on HFSS food and drink advertising to include 10- to 15-year-olds has been done without consultation.
This judgment opens up a whole new debate because, in our view, 10- to 15-year-olds are completely different from under 9-year-olds.
"We will actively engage in the very short consultation period that has been offered to us to voice our concerns and offer alternative solutions to ensure that we can continue to make a significant contribution to broadcasting in the UK."
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