A Manhattan judge on Wednesday denied the government’s request to unseal grand jury testimony from the prosecution of the disgraced financier Jeffrey Epstein, as President Trump tried to dispel criticism and conspiracy theories from his supporters.

Mr. Epstein, a financier who moved in some of America’s most exclusive circles, was indicted in 2019 on sex trafficking charges. In his 14-page opinion, Judge Richard M. Berman said that the only witness presented to the grand jury had been a single F.B.I. agent.

The information in the transcripts, Judge Berman said, “pales in comparison to the investigation information and materials in the hands of the Department of Justice.”

The chairman of the House of Representatives’ main investigative committee said this week that the Justice Department would begin providing some files about the Epstein case to lawmakers on Friday.

Judge Berman’s opinion about the transcripts came about a week after a different Manhattan judge denied the government’s request to unseal grand jury transcripts from its investigation into Ghislaine Maxwell, a longtime companion of Mr. Epstein. Ms. Maxwell is serving a 20-year prison sentence for sexually exploiting and abusing teenage girls in concert with Mr. Epstein.

On Wednesday, Judge Berman said that although Trump’s Justice Department argued that there was precedent for unsealing grand jury testimony, the government had failed to demonstrate any “special circumstances” that would justify it in the Epstein case.

In the six years since Mr. Epstein was found dead in his jail cell at the Metropolitan Detention Center while awaiting trial, his death has inspired myriad conspiracy theories.

His proximity to powerful people inspired conspiracy theorists who have promoted the idea that America is controlled by a cabal of politicians and the wealthy. His death in federal custody, which was ruled a suicide, has also spurred improbable notions about an assassination.

Top aides to Mr. Trump championed some of those theories before they entered government, and Mr. Trump had promised to release information about the investigation. However, the administration’s failure to disclose any revelations has threatened to drive a wedge between the president and some of his most fervent supporters.

This is a developing story and will be updated.