A few officers punched the hands of marchers gripping the barricades. Then, a burst of pepper spray sent many of the demonstrators reeling backward.

The police said three protesters had been arrested by 7 p.m. The bulk of the arrests took place over the next couple of hours, as several dozen protesters ignored orders to disperse and sat in the middle of Broadway. Officers surrounded them as others on the sidewalk chanted, “We believe that we will win.” Then officers began arresting those in the street and leading them away. There were no reports of injuries, the police said.

The participants had begun marching late Monday morning from Battery Park to Wall Street to protest the role they say investments in companies with practices that damage the environment play in encouraging climate change.

Streaming out of the park, protesters made a sharp turn onto Broadway, and marched north between idling buses and trucks, chanting, “The people are rising, no more compromising.” They stopped just north of Bowling Green, blocking Broadway up to Morris Street.