Bratton promised an investigation. "Quite frankly, I was disturbed at what I saw," Bratton told KNX-AM. He said the actions of some officers "were inappropriate in terms of use of batons and possible use of nonlethal rounds fired."
The Police Commission, a five-member board appointed by the mayor, has opened its own investigation, said panel spokeswoman Tami Catania.
Officers who violated department policy could receive discipline ranging from written warnings to dismissal .
Andre Birotte, the department's inspector general, said his office was trying to determine what officers said to disperse the crowd and whether the order was in Spanish -- the native language of most of the protesters.
Rally organizers denounced the police actions as brutal and unnecessary, and expressed concern over what the clash could mean for an immigration rights movement known for its peaceful rallies.
The clash at MacArthur Park started after 6 p.m. when police tried to disperse demonstrators who had moved off the sidewalk onto the street. Authorities said several of the few thousand people still at the rally threw rocks and bottles at officers, who fired rubber bullets and used batons to push the crowd back onto the sidewalk.
Several people, including about a dozen officers, were hurt. About 10 people were taken to hospitals for treatment of injuries , authorities said. None of the injuries was believed to be serious. At least one person was arrested, but police have not released a name.
