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James Blake, who was arrested in Midtown Manhattan on Sept. 9 in a case of mistaken identity, spoke to reporters in front of City Hall on Monday.Credit Michael Nagle for The New York Times

After an hourlong meeting on Monday with Mayor Bill de Blasio and Police Commissioner William J. Bratton, the retired tennis star James Blake said that the mayor had been broadly sympathetic to his calls for greater police accountability.

Speaking at a news conference outside City Hall, Mr. Blake said of the mayor, “What he said that made me feel good was that in his heart he was on the same page as us” on issues of reducing crime and instituting stronger accountability for officers.

Mr. Blake said he still thought often about being dragged to the ground by a plainclothes officer who mistook him for a suspect on a Midtown Manhattan sidewalk on Sept. 9. But, referring to Mr. de Blasio, Mr. Blake said he was heartened by “the fact that he can look me in the eye and tell me that he is on our side, and that he is looking to make a long-lasting impact.”

The meeting was a sign of how Mr. Blake’s star power and the rough treatment he faced have given him unusual clout amid a national reckoning with police misconduct. The arrest prompted swift apologies from Mr. de Blasio and Mr. Bratton, and drew renewed attention to the aggressive arrest tactics that many black New Yorkers say they face frequently, with little hope of winning an audience with the mayor.

“This afternoon, we had a productive conversation with Mr. Blake about strengthening the relationship between police and communities across our city,” Mr. de Blasio and Mr. Bratton said in a statement on Monday night. “It was based on a shared commitment to accountability and a desire to build trust. We pledged a fair and expeditious investigation into his case, and to find further common ground as we continue the work of reform.”

Even amid major preparations for a visit this week by Pope Francis, the mayor and police commissioner listened intently as Mr. Blake described the departmental policy changes he wants instituted, Mr. Blake and his lawyer, Kevin Marino, said after the meeting.

Mr. Marino said he planned to meet with the city’s corporation counsel in the coming days to discuss police reforms the city could undertake that would head off a lawsuit over the takedown, which was captured on a hotel surveillance video.

On Monday, they discussed “ways in which the department might adopt reforms that would limit incidents of this type or minimize them,” particularly by increasing accountability and curbing excessive use of force, Mr. Marino said in an interview. He added that he and Mr. Blake were “pleasantly surprised” about the reception they received from the mayor and the police commissioner.

Mr. Blake, who is biracial, did not go into detail about his proposals on Monday. But in an interview a few days after his arrest, he said that he wanted the department to rapidly expand the number of officers wearing body cameras, make a financial commitment to helping victims of police brutality and institute stronger punishments for officers who violate department policy.

He also called for the officer who tackled him, James Frascatore, to be fired, though he said on Monday that he understood the officer had due process rights and would await the conclusion of the department’s disciplinary process.

Mr. Blake also acknowledged that any reforms would face steep bureaucratic hurdles, saying he did not want to outline his specific proposals “because you don’t know what can be done logistically, how quickly it can be done.” The department’s body camera program, for example, is already poised to expand as part of a pilot program overseen by a court-appointed federal monitor, a change that would not take place until next year.

Mr. Bratton, asked about further disciplinary action against Officer Frascatore during a briefing earlier on Monday, said, “I’ll be making that final determination, and so I’m not going to speak to that at all.”

Mr. Bratton also said the officer “had not gone through the most recent three-day in-service training that we have been providing,” referring to a course that officers are required to take to improve how they relate to residents. At least seven people have given accounts of being treated harshly without explanation by Officer Frascatore in 2012 or 2013.

The unusual speed with which Mr. de Blasio, a Democrat, and Mr. Bratton initially apologized to Mr. Blake, and then agreed to the wide-ranging meeting on Monday, signaled just how seriously top city officials are treating his concerns.

Mr. Blake, a former top 10 tennis star, has waved off suggestions that he was racially profiled, and has spoken about the episode with a trademark analytical demeanor. His approach has quickly made him one of the most influential voices on police reform in New York City, a role that he said on Monday he wanted to use to bring lasting change to the Police Department.

“We’re looking for lasting, positive impact on the city and on the police force,” Mr. Blake said, adding that his priority was on reforms, rather than a possibly lucrative lawsuit. “I’m going to try to react to it in a positive manner and make a difference for all those that may not have the same situation.”