The judge presiding over the civil fraud trial of Donald J. Trump on Wednesday signaled that he might again punish the former president for violating a gag order that bars Mr. Trump from attacking court staff.
The judge, Arthur F. Engoron, has already fined Mr. Trump for comments he made about his law clerk, Allison Greenfield, whom the former president was barred from discussing after he attacked her on social media in the trial’s opening days.
During a break in the proceedings on Wednesday, Mr. Trump called Justice Engoron partisan — which is allowable under the order. But he continued, saying, “with a person who’s very partisan sitting alongside him. Perhaps even much more partisan than he is.”
After the break, the judge said he was concerned that the overheated environment in the courtroom could result in real danger.
“I am very protective of my staff,” Justice Engoron said, adding, “I don’t want anyone to get killed.”
A lawyer for Mr. Trump, Christopher M. Kise, protested that the former president had actually been referring to his former fixer, Michael D. Cohen, who was testifying for a second day. Mr. Trump did clearly refer to Mr. Cohen immediately after the initial comment, calling him a “discredited witness.”
The judge responded that the target of the comments had seemed clear to him, but that he would take the matter under advisement. When he fined Mr. Trump $5,000 last week, an amount that on Wednesday he called “minimal,” he issued a written order explaining his decision after the trial had ended for the day.
That violation was something of a technicality: Though the comments about Ms. Greenfield were deleted from social media, they had also been posted to Mr. Trump’s website and were not taken down for weeks.
By contrast, Mr. Trump made his statement Wednesday to reporters in the hall outside the courtroom, where he typically addresses television cameras. It demonstrated the danger of the gag order to a former president known for spontaneous monologues in which he attacks his enemies.
The trial, which stems from a lawsuit filed against Mr. Trump by the New York attorney general, Letitia James, centers on the former president’s annual financial statements, where he listed his net worth.
Mr. Cohen is chief among the former president’s enemies. He once worked as a fixer for Mr. Trump. But after breaking with the then-president in 2018, Mr. Cohen testified before Congress that the financial statements were filled with fraudulent values, which had been calculated to reach Mr. Trump’s desired overall net worth.
He said the same thing on his first day of testimony at the trial on Tuesday, when questioned by a lawyer from the attorney general’s office. He also spoke about his involvement in deals in which Mr. Trump’s annual financial statements — where the fraudulent values were listed — were used to showcase the former president’s wealth and financial power.
The sudden drama at the midmorning break interrupted lawyers for Mr. Trump as they tried to impugn Mr. Cohen, with Mr. Kise calling him a “perjurious witness who has lied to everyone he’s ever spoken to.”
From the witness stand, Mr. Cohen clashed with another of Mr. Trump’s lawyers, Alina Habba. She suggested that Mr. Cohen had been inconsistent in his descriptions of his work on the financial statements. For example, she noted that he said in a deposition that he had worked on “almost every asset,” whereas at the trial, he said that he had worked on a limited number.
She then moved on to questioning Mr. Cohen’s overall credibility, introducing evidence from before 2018 in which Mr. Cohen praised Mr. Trump and a text message he had sent about his interest in becoming the White House chief of staff.
Mr. Cohen’s relationship with Mr. Trump, for whom he once said he would take a bullet, soured after federal prosecutors began to investigate a 2016 hush money payment to a porn star that he made on Mr. Trump’s behalf. Mr. Trump began to distance himself from his former fixer, and, eventually, Mr. Cohen turned on him, and began to speak with prosecutors who were looking into the then-president’s conduct.
Mr. Cohen’s testimony has energized the trial, which has lasted three weeks. Justice Engoron has already ruled that Mr. Trump committed fraud by inflating the value of his properties to receive better treatment from banks and insurance companies.
The trial will determine whether the former president’s conduct and that of other defendants, including two of his adult children and his company, violated other laws, and whether he has to pay a financial penalty. Ms. James has asked that he be fined $250 million.
Because the central claim of the trial has already been decided, there has been little day-to-day drama, other than that injected by Mr. Trump’s frequent visits to the courthouse — and his free-ranging comments in the hallways, where he made the comment that on Wednesday may have caused him more trouble.