US President Donald Trump has bashed media coverage that he claimed was unduly negative and therefore "illegal", stoking a debate over free speech following the suspension of comedian Jimmy Kimmel's TV show by ABC.

"They'll take a great story and they'll make it bad. See I think it's really illegal, personally," Trump, who has sued multiple major news organisations this year, said in the Oval Office on Friday.

The 79-year-old Republican, an avid television watcher, chiefly focused his diatribe on US television networks, reiterating a claim that coverage of him and his administration is "97 percent bad".

He also defended the head of the Federal Communications Commission, Brendan Carr, whose threats against broadcasters have sparked a national debate over free speech and caused some unease even among Republicans.

Carr on Wednesday criticised Kimmel's remarks on the assassination of conservative activist Charlie Kirk and threatened broadcasters who carry his show with possible sanctions. Hours later, ABC announced Kimmel's show was suspended indefinitely.

On Friday, Trump called Carr "an incredible American patriot with courage."

Texas senator Ted Cruz, a close Trump ally, meanwhile said he believes it's dangerous for a government to put itself in a position to say what speech it may or may not like.

Commenting on Carr's threat to fine broadcasters or pull their licenses over the content of their shows, Cruz referenced a Martin Scorsese gangster movie.

"I got to say that's right out of 'Goodfellas'," he said. "That's right out of a mafioso coming into a bar going, 'Nice bar you have here. It would be a shame if something happened to it.'"

Trump himself faced a setback in his personal anti-media crusade, with a federal judge issuing a scathing ruling and tossing out his US$15 billion defamation lawsuit against The New York Times. (AFP)