The New York judge presiding over Donald J. Trump’s civil fraud trial ordered the former president Tuesday not to attack or even comment on court staff after Mr. Trump posted a message to social media targeting the judge’s law clerk.
Mr. Trump went after the clerk, Allison Greenfield, shortly before noon on his Truth Social site. His post was a picture of Ms. Greenfield with Senator Chuck Schumer, the Democratic majority leader. Mr. Trump mocked Ms. Greenfield as “Schumer’s girlfriend” and said that the case against him should be dismissed.
Mr. Trump posted his message in the midst of a trial in which he is accused by the New York attorney general, Letitia James, of inflating the value of his assets in his annual financial statements to gain favorable treatment from banks and insurance companies.
The post was taken down during a lunch break, shortly after a closed-door meeting between the parties in the room where Mr. Trump is being tried.
After the break, the judge, Arthur F. Engoron, explained what had happened, though he did not name Ms. Greenfield or Mr. Trump, referring to the former president only as a defendant.
“Personal attacks on members of my court staff are unacceptable, inappropriate and I will not tolerate them under any circumstances,” the judge said.
Justice Engoron said that his statement should be considered a “gag order” forbidding any posts, emails or public remarks about members of his staff. He added that serious sanctions would follow were he to be disobeyed. He did not elaborate, but experts said that if the former president violates the order, the judge could fine Mr. Trump as much as $1,000 — or even hold him in jail for up to 30 days, though the chances of that happening are slim.
The former president’s social media posts have become an issue in several cases against him. Federal prosecutors who have accused Mr. Trump of seeking to overturn the 2020 election have asked a judge for a gag order, citing his threatening statements. In a criminal case against Mr. Trump in Manhattan that stems from a 2016 hush money payment to a porn star, the judge has restricted Mr. Trump’s ability to post about some evidence.
Mr. Trump has spent much of the first two days of his civil fraud trial attacking Justice Engoron and Ms. James, both Democrats. Last year, Ms. James filed the lawsuit that led to the trial, accusing Mr. Trump of “staggering fraud” by inflating the values of his assets.
In a pretrial ruling, Justice Engoron found that the former president was liable for fraud and dissolved the companies he uses to run his New York properties. What remains to be determined at trial is whether the former president and his fellow defendants are liable for other illegal acts and whether there will be further punishment. Ms. James has asked Justice Engoron to fine the defendants $250 million.
Mr. Trump has called the judge “deranged” and said that he is biased. His attack on Ms. Greenfield, which also included a link to what appeared to be Ms. Greenfield’s Instagram account, pushed the idea of Democratic collusion against him, saying that the case should be dismissed immediately.
In a statement, a spokeswoman for Senator Schumer called the post “ridiculous, absurd, and false.”
“Senator Schumer does not know Ms. Greenfield,” the statement said. “As is well known, Senator Schumer attends countless events in every corner of the state where tens of thousands of constituents take photos with him, just like this one, which was taken at a stop at an annual brunch in Manhattan.”
Justice Engoron is known for keeping a lighthearted atmosphere in his courtroom, cracking jokes and making outdated pop culture references. On Tuesday, after news photographers snapped picture after picture of Mr. Trump, Justice Engoron remarked, “Oh, the wages of fame.”
He also gives unusual latitude to Ms. Greenfield, allowing her the occasional direct question to lawyers. The two have a rapport: Justice Engoron makes jokes and quips and Ms. Greenfield keeps the trains running on time
But the judge spoke gravely Tuesday as he explained the terms of his order. He noted that while Mr. Trump had taken down the Truth Social post about Ms. Greenfield, the former president’s campaign had sent out a copy in an email to millions of people.
The trial resumed soon after the judge’s stern warning with the cross-examination of a retired accountant who used to work with Mr. Trump. And Justice Engoron recovered his usual bearing quickly. Soon, he was correcting one of Mr. Trump’s lawyers on the proper pronunciation of triplex, leading many in the courtroom — Ms. James included — to laugh.
As for Mr. Trump, he sat quietly during the afternoon, occasionally making comments to his lawyers as he watched one aggressively question the accountant, Donald Bender.
After court concluded, he did not respond to questions about the judge’s order but said he would return to the trial Wednesday.
Ben Protess contributed reporting.