The New York judge overseeing Donald J. Trump’s criminal trial later this month expanded a gag order on Monday to bar the former president from attacking the judge’s family members, who in recent days have become the target of Mr. Trump’s abuse.

Justice Juan M. Merchan last week issued an order prohibiting Mr. Trump from attacking witnesses, prosecutors, jurors and court staff, as well as their relatives. That order, however, did not cover Justice Merchan himself or the Manhattan district attorney, Alvin L. Bragg, who brought the criminal case against the former president.

And although the ruling issued on Monday still does not apply to the judge or the district attorney, Justice Merchan, granting a request from Mr. Bragg’s office, amended the gag order so that it does now cover their families.

In his ruling, the judge cited recent attacks against his daughter, and rejected Mr. Trump’s argument that his statements were “core political speech.”

“This pattern of attacking family members of presiding jurists and attorneys assigned to his cases serves no legitimate purpose,” Justice Merchan wrote. “It merely injects fear in those assigned or called to participate in the proceedings, that not only they, but their family members as well, are ‘fair game’ for defendant’s vitriol.”

Mr. Bragg’s office had asked the judge to clarify that their relatives were included, calling such protection “amply warranted.” Noting Mr. Trump’s track record of issuing “threatening and alarming remarks,” Mr. Bragg’s office warned of “the harms that those family members have suffered.”

The personal connection to the gag order complicated Justice Merchan’s decision. Shortly after last week’s initial gag order, Mr. Trump issued a series of blistering attacks on Mr. Merchan and his daughter, Loren, a political consultant who has worked with Democratic candidates.

Specifically, Mr. Trump had accused Ms. Merchan — falsely — of having posted a photo of him behind bars on an account on X, the platform formerly known as Twitter. Court officials said the account cited by Mr. Trump had been taken over last year by someone other than Ms. Merchan.

On Thursday, Mr. Trump intensified his attacks, identifying Justice Merchan’s daughter by name and accusing her of being “a Rabid Trump Hater, who has admitted to having conversations with her father about me, and yet he gagged me.” The former president then renewed his demands that the judge recuse himself from the case, calling Justice Merchan “totally compromised.”

And on Saturday, in an ominous escalation, Mr. Trump posted a news article to Truth Social that displayed two pictures of Ms. Merchan.

Mr. Trump, the first former American president to face criminal prosecution, is scheduled to go on trial on April 15. Mr. Bragg charged him with 34 felony counts of falsifying business records related to the cover-up of a sexual scandal involving a porn star, Stormy Daniels.

Mr. Trump, once again the presumptive Republican nominee for president, has denied the affair and the charges, which he claims are politically motivated. Mr. Trump and his campaign have also lashed out at the gag order, calling it “unconstitutional.” And his lawyers argued against expanding the gag order to include Justice Merchan and Mr. Bragg’s family, noting that the original order did not cover the judge or the district attorney.

Todd Blanche, one of Mr. Trump’s lawyers, declined to comment on Monday.

Steven Cheung, a spokesman for Mr. Trump’s campaign, called the judge’s amended gag order “unconstitutional,” because, he said, it prevents Mr. Trump from engaging in political speech, “which is entitled to the highest level of protection under the First Amendment.” He added, “The voters of America have a fundamental right to hear the uncensored voice of the leading candidate for the highest office in the land.”

Justice Merchan is just the latest judge to impose a gag order on the former president. A federal appeals court upheld a gag order in Mr. Trump’s federal criminal case in Washington, where he is accused of plotting to overturn the 2020 election.

And in his civil fraud case in New York, Mr. Trump was ordered not to comment on court staff members after he attacked the judge’s principal law clerk. The judge, Arthur F. Engoron, imposed $15,000 in fines on the former president when he ran afoul of that order.

If Mr. Trump violates Justice Merchan’s order, the judge could impose fines, and in extraordinary circumstances, throw him behind bars.

Mr. Bragg’s office had asked the judge to warn Mr. Trump that he will be punished if he ignores the order, using stark language that underscored the state’s concern about the former president’s words.

“Defendant’s dangerous, violent and reprehensible rhetoric fundamentally threatens the integrity of these proceedings and is intended to intimidate witnesses and trial participants alike — including this court,” Mr. Bragg’s office wrote.

In his five-page ruling, Justice Merchan noted that Mr. Trump had a right “to speak to the American voters freely and to defend himself publicly.” But he sought to balance those rights with the impact of Mr. Trump’s statements on the trial.

“It is no longer just a mere possibility or a reasonable likelihood that there exists a threat to the integrity of the judicial proceedings,” the judge wrote. “The threat is very real.”

Kate Christobek contributed reporting.