Ministers are currently considering the introduction of so-called 'fair use' principles, meaning websites such as Google's YouTube would be able to show clips of popular TV shows.
ITV chief executive Adam Crozier said that culture secretary Jeremy Hunt and business secretary Vince Cable were told at a recent meeting of the creative industries that broadcasters and producers are vigorously opposed to the move.
Speaking to the Financial Times, Crozier said that the government must protect intellectual property (IP) if it genuinely wants to support the creative industries and make Britain a world leader in TV production.
"If the government really sees creative Britain as being a growth story, the surest way to pull the rug out from under it would be to weaken the IP rules," said Crozier.
"And I think what happened is that [the TV industry] hasn't been joined-up enough to focus on this."
The ITV chief executive does not believe there can be a compromise on fair use policies, as hit shows such as Downton Abbey rely on secondary rights such as online to make money.
"This is the absolute underpinning that allows this industry to work," said Crozier.
Crozier, who guided ITV to a pre-tax profit of £321m last year, expressed his fear that "a number of companies had done a potentially better job at influencing around 'fair use' and those tended to be the companies that weren't investing in creating content".
He also called on the government to prioritise firms "paying British taxes, creating British jobs, creating an export market and ancillary markets that come from that".
Professor Ian Hargreaves has been appointed by the government to review IP laws, with the 'fair use' rules a key component of his investigation.
Last month, Crozier confirmed that ITV is considering a major acquisition of an independent production company to boost the fortunes of ITV Studios.