Two days after protesters injured two police lieutenants in a melee on the Brooklyn Bridge, Police Commissioner William J. Bratton said on Monday that such assaults on officers would bring a firm response.

“We do not take attacks on our police officers lightly,” he said in a news conference at Police Headquarters. “Never have; never will.”

His comments came as detectives sought six additional suspects in the bridge attack on Saturday and hours after police commanders met to consider recalibrating the department’s hands-off approach to demonstrators in order to prevent future clashes while continuing to allow for peaceful marchers.

Mr. Bratton said 331 arrests had occurred, including six for assaults on officers, since the start of large-scale demonstrations over a Staten Island grand jury’s decision not to indict an officer in the death of Eric Garner and a similar decision by a Missouri grand jury in the fatal shooting of Michael Brown. Both were unarmed black men killed by white officers.