A “street organizing” coalition that briefly blocked rush hour traffic in front of Madison Square Garden yesterday evening to protest the acquittal of three detectives in the shooting of Sean Bell said the demonstration was the beginning of disruptions planned for the city.

Members of the groups said that besides being “very loud and chaotic,” they wanted to urge the comedian Chris Rock, who was performing at the arena, and other black celebrities to join in the protests against the verdict.

“This is a civil disobedience. We’re not getting permits, we’re going places we’re not supposed to be,” one of the organizers, Salaam Ismial, said. “We’re looking for the endorsement of Chris Rock.”

He said the groups are a coalition of grassroots community organizations that include Communities United Against Police Brutality and Mr. Ismial’s own organization, the United Youth Council, which joined together this week after a judge acquitted the police detectives who fatally shot Bell in 2006.

Shouting “no justice, no peace” and counting down the number of bullets fired at Bell — 50 — the protesters blocked an M4 bus and a sea of yellow taxis traveling on Seventh Avenue for about 10 minutes. Although police were present, no one was arrested.

The Reverend Al Sharpton has been promising to shut down the city with protests, but he and the Bell family were not present yesterday.

Bell’s family and friends have held several news conferences in recent days to denounce the verdict and also have promised major actions. They have enlisted the help of federal lawmakers, including nearly a dozen members of Congress, to examine how the federal government might get involved in the case.

Earlier yesterday, the police commissioner, Raymond Kelly, said he did not expect any violence. Representatives for Mr. Rock and for Madison Square Garden did not immediately return messages seeking comment.