News organizations and free speech groups reacted with outrage and defiance on Wednesday to a report that President Trump had asked the former F.B.I. director, James B. Comey, to consider jailing American journalists who published classified information about the government.

Mr. Trump’s suggestion, reported in a New York Times article on Tuesday based on a memo that Mr. Comey wrote shortly after a Feb. 14 meeting between the two men in the Oval Office, was a stark summation of the president’s dislike of the news media, and press advocates said it represented the kind of draconian tactic often used by autocratic regimes.

“We’ve been saying there’s a big gap between the president’s rhetoric and actions he can take to undermine the work of the media,” said Joel Simon, executive director of the Committee to Protect Journalists. “That gap has now been closed.”

Mr. Trump was fixated during the Feb. 14 meeting on a series of damaging leaks about his administration, including the disclosure that his national security adviser had been recorded on an F.B.I. wiretap speaking with Russia’s ambassador to the United States, according to one of Mr. Comey’s associates. The topic led Mr. Trump to suggest that Mr. Comey consider putting reporters in prison for disseminating classified information, the associate said, according to The Times’s article.

“Suggesting that the government should prosecute journalists for the publication of classified information is very menacing, and I think that’s exactly what they intend,” said Martin Baron, The Washington Post’s executive editor. “It’s an act of intimidation.”

For their part, right-leaning media outlets have looked warily at the mainstream media, frequently adopting Mr. Trump’s view that negative news about his administration is “fake news.” And the conservative media has seized on major news stories critical of Mr. Trump as proof that left-leaning media wants to sabotage the president.

“They want to bring down this presidency — and will do and say anything to overthrow this duly elected leader. Anything,” the conservative commentator Todd Starnes wrote on Fox News’s website.

“Some journalists are seething with so much rage and hatred,” Mr. Starnes wrote, “I would not put it past them to do whatever they deem is necessary to destroy the Trump presidency — even if it means writing fake news stories and using anonymous sources.’’

Mr. Trump often rails against the journalists and news organizations that cover him, invoking the “fake news” term in public appearances and on social media. As a former reality television star fixated on the media, the president also grants interviews to those same news organizations. His comments to Mr. Comey about imprisoning journalists could be construed as a private fit of pique, or as a more concerted effort to enlist the Justice Department in quashing reporting that the president dislikes.

The White House did not respond on Wednesday when asked whether Mr. Trump still supported imprisoning reporters. The president’s press secretary, Sean Spicer, told reporters on Air Force One that Mr. Trump did not believe that The Times’s article “was an accurate representation of that meeting.”

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The president returned to the theme on Wednesday during an address at the Coast Guard Academy. “No politician in history has been treated worse or more unfairly” by the media, he said.

Mr. Trump is not the first president that journalism groups have accused of impinging on press freedoms. The Obama administration was harshly criticized by news organizations for pursuing aggressive prosecutions of suspected government leakers, investigations that occasionally ensnared the journalists involved.

Still, Mr. Trump’s record of flouting political norms — and his expressions of disdain toward the press, as when he declared some news organizations to be “the enemy of the American people” — has worried journalists who believe he is more willing to take drastic steps to stifle reporting.

“Jailing reporters would put us on par with nations like Turkey and China,” said Robert J. Byers, executive editor of the Charleston Gazette-Mail in West Virginia, which won a Pulitzer Prize this year. The president’s suggestion that reporters be jailed, Mr. Byers said, is “just one more way that President Trump has shown his lack of understanding of the role of the press in a free society.”

Joseph Kahn, the managing editor of The Times, said in a statement: “We believe strongly that it is in the public interest to have a vigorous media committed to publishing truthful information about the government. The First Amendment clearly protects the right of the press to publish such information, and The Times regards fair, unfettered coverage of those who hold power as a core part of its mission.”

The government has never charged a reporter under the Espionage Act. But previous administrations have flirted with the possibility.

After The Times exposed the National Security Agency’s warrantless surveillance program during President George W. Bush’s administration, Alberto Gonzales, the attorney general at the time, publicly raised the possibility of prosecution. Though the Justice Department launched an aggressive investigation into that leak, no one was ever charged.

That increased focus on leaks carried over into the Obama administration, which brought about nine cases against leakers — about twice as many as all previous administrations combined. The administration never charged journalists, but its aggressive investigative tactics in several cases attracted a backlash.

In 2013, the Justice Department identified a Fox News reporter, James Rosen, “as an aider, abettor and/or co‑conspirator” in a leak by State Department officials of information about North Korea. Justice Department officials said they never contemplated charging Mr. Rosen, and merely wanted access to his email account. But Congress and news organizations vehemently protested, prompting Attorney General Eric H. Holder Jr. to revised the Justice Department’s rules for leak investigations and to add protections for reporters.

Mr. Holder also fought to the Supreme Court to try to force a Times reporter, James Risen, to testify as a witness in the trial of a former C.I.A. official accused of leaking classified information to him about Iran’s nuclear program. Mr. Risen vowed to go to prison for contempt rather than provide information. In the end, the Justice Department did not carry out its threat.

“What happened during the Obama administration was an investigation of leaks and leakers,” Mr. Baron of The Post said. “This is of a different order because what he’s talking about here is actually prosecuting journalists directly for receiving and publishing information that is confidential and in some instances classified.”

Charles Savage contributed reporting.