In her first public appearance since James B. Comey, the former F.B.I. director, began his book tour, Hillary Clinton made only a glancing reference to him in a speech on Sunday night and instead focused most of her attacks on President Trump, once again likening him to authoritarians.

Mrs. Clinton gave the Arthur Miller Freedom to Write Lecture at PEN America’s World Voices Festival in New York City. She spoke at length about threats to journalists around the world before turning her attention to domestic matters. She criticized Mr. Trump, not so subtly comparing him to authoritarian leaders who had suppressed journalism in their countries.

“Today, we have a president who seems to reject the role of a free press in our democracy,” she said. “Although obsessed with his own press coverage, he evaluates it based not on whether it provides knowledge or understanding, but solely on whether the daily coverage helps him and hurts his opponents.”

After listing more examples of Mr. Trump’s attacks on the news media, Mrs. Clinton said, “Now given his track record, is it any surprise that, according to the latest round of revelations, he joked about throwing reporters in jail to make them ‘talk’?”

She was referring to the newly declassified memos that Mr. Comey kept, recounting his private conversations with Mr. Trump.

According to those notes, Mr. Comey and Mr. Trump agreed that those who leaked classified information should be aggressively prosecuted. Mr. Comey said he was in favor of “putting a head on a pike as a message.”

Mr. Trump, according to Mr. Comey’s telling, suggested that reporters who publish the leaks should be jailed, adding: “They spend a couple days in jail, make a new friend, and they are ready to talk.”

Mrs. Clinton and Mr. Trump have exchanged barbs since he entered the White House. She has repeatedly questioned his fitness for office, and Mr. Trump has frequently called her “Crooked Hillary” in posts on Twitter.

After her remarks, which were at the Cooper Union, Mrs. Clinton participated in an onstage interview with the author Chimamanda Ngozi Adichie. During the conversation, Mrs. Clinton revisited her election loss at great length. When Ms. Adichie asked if Mrs. Clinton had fought back enough during the campaign, the former Democratic nominee conceded that she had not.

“I was really struggling with it, and I concluded — as I was, I think, expecting myself to — ‘O.K., you just have to be calm and in control because ultimately, what the country wants is somebody who is not going to be blowing up in the Oval Office,’” Mrs. Clinton said.

She went on: “They want somebody who is going to be able to deal with the problems. Well, you know that did not work out so well.”

The White House did not respond to a request for comment.