"Three officers violently attacked by protesters crossing the Brooklyn Bridge. The officers sustained serious injuries," the department said in a Twitter message. "This is not a peaceful protest, this will not be tolerated."
Clashes between Black Lives Matter and pro-police demonstrators erupted on the bridge earlier in the day.
Mayor Bill de Blasio on Wednesday ended a curfew he imposed last week. He also promised to cut the NYPD's budget and turn over some of the money saved to social services as the protesters have demanded.