Donald Trump speaks Saturday in Houston. (Mandel Ngan/AFP/Getty Images)

New York Times columnist Maureen Dowd says that she doesn't hesitate to confront Republican presidential nominee Donald Trump about what she considers "unacceptable behavior," including seeming to incite violence at his rallies.

"I told him that it was wrong that there was violence being incited at his rallies and that reporters were getting roughed up," Dowd said during an interview on CNN on Saturday to promote her new book, "The Year of Voting Dangerously." "And he paused — you're right, he did listen — but then he disagreed and said he thought the violence added a frisson of excitement."

Dowd said she also confronted Trump for highlighting former President Bill Clinton's infidelities when his own marriages have not been perfect. And she described Trump's new campaign manager in this way: "I picture Kellyanne Conway like a lion tamer trying to keep Donald Trump on his stool."

Trump fired back at Dowd and the New York Times on Twitter on Saturday afternoon, although it was unclear if he was responding to Dowd's CNN interview or something else. He twice accused Dowd of not knowing him as well as she claims and also called her "wacky," "crazy" and "a neurotic dope" whose interviews are "boring."

When it comes to violence at his rallies, Trump often tells his crowds to not harm protesters who interrupt him — but he has also offered to pay the legal expenses of supporters who attack protesters, praised a supporter who punched a protester dressed in a Ku Klux Klan hood and criticized the police for handling protesters too gingerly. When a Black Lives Matter activist was harmed at a Trump rally in Birmingham, Ala., in November, Trump said that the man was “so obnoxious and so loud” that “maybe he should have been roughed up.”

Trump insists that his rallies are the safest places on earth and when chaos breaks out at one of his rowdy rallies, Trump will often marvel at the scene and say: "Is there anything more fun than a Trump rally?"

Dowd wasn't Trump's only target on Twitter on Saturday. He also went after former Defense Secretary Robert Gates, who wrote in a Wall Street Journal op-ed that published online on Friday evening that Trump is "unqualified and unfit to be commander-in-chief."

“At least on national security, I believe Mr. Trump is beyond repair," Gates wrote. "He is stubbornly uninformed about the world and how to lead our country and government, and temperamentally unsuited to lead our men and women in uniform. He is unqualified and unfit to be commander-in-chief."

Trump's response to Gates was similar to his tweets about Dowd, with Trump writing: He knows nothing about me."

And Trump went after CNN and the New York Times, frequent recipients of his ongoing frustration with the media.