Mayor Eric Adams released a videotaped speech late Wednesday, calling any federal charges against him “entirely false” and “based on lies.”

Mr. Adams, a Democrat who is running for re-election next year, stood in front of an American flag as he spoke to New Yorkers and took a somber tone. He appeared to be speaking at Gracie Mansion; it appeared that he recorded the video before he knew he had been indicted.

“If I am charged, I know I am innocent,” he said. “I will request an immediate trial so that New Yorkers can hear the truth.”

Mr. Adams, the city’s second Black mayor, won a competitive Democratic primary in 2021 on a public safety message. As a former police officer, he has said that he follows the law and instructs city officials to do the same.

He vowed to continue as mayor despite a series of high-profile departures from his administration, including his police commissioner, schools chancellor and health commissioner.

“I will fight these injustices with every ounce of my strength and my spirit,” he said, his demeanor alternating from sober to indignant.

Mr. Adams has had a rocky relationship with the Biden administration over the migrant crisis, and the mayor has warned that it would destroy New York City. He mentioned that battle as an example of how he had fought injustices during his career and appeared to suggest that it might be a reason he was targeted.

“Despite our pleas, when the federal government did nothing as its broken immigration policies overloaded our shelter system with no relief, I put the people of New York before party and politics,” he said.

Mr. Adams ended the speech with a reference to his faith, a central part of his biography. The mayor has said that God told him that he would be mayor.

“I humbly ask for your prayers and your patience as we see this through,” he said. “God bless you and God bless the city of New York.”