US District Judge Lewis Kaplan's threat came after a lawyer for Carroll said Trump was talking loudly with his lawyers during Carroll's testimony on Wednesday.
Carroll, who wrote an advice column for Elle magazine for 27 years, says Trump destroyed her reputation and should pay millions of dollars in damages for denying in 2019 that he had raped her nearly a quarter of a century earlier.
"He said: 'It is a witch hunt, it really is a con job,'" Carroll's lawyer Shawn Crowley said outside the jury's presence in federal court in Manhattan.
Kaplan warned Trump to control himself during the trial.
"Mr Tump has the right to be present here," Kaplan said. "That right can be forfeited and it can be forfeited if he is disruptive ... and if he disregards court orders.
"Mr Trump, I hope I don't have to consider excluding you from the trial," the judge continued. "I understand you are probably very eager for me to do that."
He skipped opening statements on Tuesday afternoon, and flew to New Hampshire for a campaign event that night.
Trump's multiple criminal and civil trials have become a focus of his 2024 White House run, with Trump using his Truth Social platform to criticise Carroll and the judge even after the trial had begun.
Following Kaplan's warning, Trump posted that Kaplan was a "seething and hostile" judge with "a major case of Trump Derangement Syndrome."
Trump often uses his legal travails to rally supporters and raise funds as he seeks the Republican presidential nomination, calling the cases part of a political plot.
He has pleaded not guilty in four state and federal criminal cases, including two claiming he tried to overturn his 2020 election loss to Democrat Joe Biden.
'HE LIED'
Wednesday's trial arose from two statements in June 2019 in which Trump denied Carroll's claim that he had raped her in a Bergdorf Goodman department store dressing room in New York.
Trump claimed he didn't know Carroll, and that she branded him a rapist to boost sales of her then-new memoir.
In May last year, a different jury ordered Trump to pay Carroll $US5 million ($NZ8.1 million), finding he had sexually abused her, and then defamed her in 2022 by denying that anything happened.
Kaplan has already ruled that Trump sexually abused Carroll by forcing his fingers into her vagina, and defamed her in his 2019 statements.
Carroll, 80, testified that lies destroyed her reputation for telling the truth, and instantaneously exposed her to online attacks, including death threats.
"I am here because Donald Trump assaulted me, and when I wrote about it, he said it never happened," Carroll said. "He lied, and it shattered my reputation."
Carroll is seeking another $US10 million in compensatory damages, plus punitive damages.
She fought back tears when her lawyer Roberta Kaplan, who is not related to the judge, showed her a message from an unknown sender suggesting that she stick a gun in her mouth and pull the trigger.
"I was attacked on Twitter, I was attacked on Facebook, I was attacked on news blogs, I was brutally attacked in messages," Carroll said. "It was a new world."
Carroll said she now gets just eight letters a month from readers seeking advice, down from 200, and that the attacks haven't let up.
"Yesterday I opened up Twitter, and it said 'hey lady, you're a fraud,'" Carroll said. "Now I'm known as a liar, a fraud and a whack job."
Asked if she regretted speaking up, Carroll said: "Only momentarily. I am very glad I took action."
Twitter is now known as X.
Trump's lawyer Alina Habba then began cross-examining Carroll, trying to show jurors that the attacks began even before Trump denied Carroll's claims, and that Carroll's income had fallen by half the year before she released her memoir.
Habba has also said Carroll has basked in adulation from supporters and attention from media since accusing Trump of rape.
Trump did not attend the first trial.
In his Truth Social post on Wednesday, Trump said he would have won that case had he attended. He also repeated his desire to attend his mother-in-law's funeral in Florida on Thursday, and criticised Kaplan's decision to hold trial that day.
The court does not sit on Friday, and Trump could testify next week.
