Nonetheless, the use of a chokehold in subduing a large but unarmed man during a low-level arrest raises for Mr. Bratton the same questions about police training and tactics that he faced 20 years ago, in his first stint as New York City’s police commissioner.

In 1994, the year after the Police Department banned chokeholds, a man named Anthony Baez died in the Bronx after a police officer put him in a chokehold during a dispute over a touch football game.

At City Hall on Friday, Mr. Bratton said he did not believe that the use of chokeholds by police officers in New York City was a widespread problem, saying this was his “first exposure” to the issue since returning as police commissioner in January.

Mayor Bill de Blasio, standing next to Mr. Bratton, said, “Like so many New Yorkers I was very troubled by the video,” referring to a bystander’s recording of the incident, which was posted on the website of The New York Daily News. The two police officers who initially confronted Mr. Garner have been temporarily taken off patrol duty. The police declined to name the officers but said one of them had been on the force for eight years and the other for four years.

Late Friday, the mayor’s office announced that Mr. de Blasio was postponing his family’s departure on a planned vacation to Italy from Friday evening until Saturday. The postponement was to allow Mr. de Blasio to spend more time making calls to elected officials, community leaders and members of the clergy, and talking to the police, about Mr. Garner’s death, the mayor’s press secretary, Phil Walzak, said.

The encounter between Mr. Garner and plainclothes officers, from the 120th Precinct, began after the officers accused Mr. Garner of illegally selling cigarettes, an accusation he was familiar with. He had been arrested more than 30 times, often accused of selling loose cigarettes bought outside the state, a common hustle designed to avoid state and city tobacco taxes. In March and again in May, he was arrested on charges of illegally selling cigarettes on the sidewalk.

For years, Mr. Garner chafed at the scrutiny by the police, which he considered harassment. In 2007, he filed a handwritten complaint in federal court accusing a police officer of conducting a cavity search of him on the street, “digging his fingers in my rectum in the middle of the street” while people passed by.