Four major television networks — ABC, CBS, NBC and CNN — have come under fire from the Trump camp for “censorship” after refusing to air a political ad over its reference to “fake news.”

Jamestown Associates, which produced the 30-second spot touting President Trump’s record during his first 100 days in office, said Friday that the networks’ decision to reject the paid ad is “unprecedented.”

“No matter your ideology, the notion of censorship should send a chill up your spine,” said the Republican political consulting firm.

“The First Amendment is first for a reason — no right is more fundamental and inherently American than freedom of speech,” said the Jamestown statement. “Yet, CNN, CBS, ABC, and NBC decided you cannot see it on their airwaves. To our knowledge, this has never happened before.”

Presidential daughter-in-law Lara Trump, a consultant for Donald J. Trump for President, which paid for the ad, denounced the move as “an unprecedented act of censorship in America that should concern every freedom-loving citizen.”

“Apparently, the mainstream media are champions of the First Amendment only when it serves their own political views,” said Ms. Trump, who is married to the president’s son Eric. “Faced with an ad that doesn’t fit their biased narrative, CNN, ABC, CBS, and NBC have now all chosen to block our ad.”

At issue is a clip showing five prominent television news personalities overlaid with the words “FAKE NEWS.”

The voice-over says that “America has rarely seen such success,” but “you wouldn’t know it from watching the news.”

Two networks — NBC and CNN — released statements saying that they would run the ad only if the phrase “fake news” were removed. CBS declined a request for comment.

“Consistent with our policies, we have agreed to accept the ad if the inaccurate graphic — which refers to journalists as ‘fake news’ — is corrected,” said an NBCUniversal spokesperson.

In its statement, CNN said that the “mainstream media is not fake news, and therefore the ad is false. Per our policy, it will be accepted only if that graphic is deleted. Those are the facts.”

The ad ran afoul of ABC’s guidelines prohibiting ads that include personal attacks and requiring political ads to be “sourced and verified.”

“We rejected the ad because it did not meet our guidelines,” said an ABC spokesperson. “We have previously accepted Trump ads and are open to doing so in the future.”

The five personalities shown in the ad — MSNBC’s Andrea Mitchell and Rachel Maddow, CNN’s Wolf Blitzer, ABC’s George Stephanopoulos and CBS’ Scott Pelley — are among Mr. Trump’s most visible critics in the media.

Fox News has aired the ad, said Jamestown creative director Len Khodorkovsky.

The $1.5 million television and digital ad campaign launched Monday.