Over the last two decades, the decline in murders in New York has been greater than in other parts of the country. (In the early 1990s, when Mr. Kelly spent a little more than a year as police commissioner, the first of his two stints in the job, the city was coping with about 2,000 murders annually.)

Mr. Kelly has long discounted much of the criticism of stop-and-frisk as coming from a small number of advocacy groups that he says are disconnected from the communities in the Bronx, north Brooklyn and parts of Queens, where his policing strategies have been focused.

But even as the police make further inroads in suppressing violence in East New York, Brooklyn, and South Jamaica, Queens, neighborhoods with an outsize share of violence, there is a sense of frustration among police officials that their results have not quelled such criticism.

Referring to the drop in crime, Mr. Kelly said on Thursday, “Some people apparently are not satisfied with that.”

His remarks came hours after the City Council passed two pieces of legislation, one that would put in place an inspector general to investigate the Police Department and another that would expand New Yorkers’ ability to sue over racial profiling by officers.

Noting how the latest reduction of violence coincided with a diminishing number of street stops, some civil rights lawyers have grown more vocal in questioning not only the legality but also the effectiveness of stop-and-frisk tactics.

But police commanders point to what they say is the long half-life of the deterrent effect of stop-and-frisk, saying that criminals may decide to leave their guns at home because they have been stopped in the past, even if the odds of a stop have decreased in recent months. And the police say the decrease in violence has most likely led to a corresponding decrease in suspicious behavior, which results in fewer stops.