A white Fort Lauderdale police officer was suspended Monday after he was captured on video shoving a black woman to the ground when she was already on her knees.
Witnesses say fellow officers instantly jumped in and pulled him away.
Fort Lauderdale Police Chief Rick Maglione says the officer has been relieved of duty while the incident is investigated.
He also praised other officers, including Krystle Smith, for moving in.
"She did what you are supposed to do. When you see either adrenaline or emotion or some kind of interaction going south ... that is our job to do, is intervene," Maglione said.
He said if any disciplinary action is needed, it will be "swift and corrective in nature."
The incident took place Sunday after what had been a peaceful demonstration turned violent, with small groups of demonstrators breaking windows and spraying graffiti on buildings.
One group of marchers surrounded an officer, while another group began jumping on a police car. The African American woman was already on her knees when Officer Steven Pohorence walked by and shoved her head, pushing her to the ground.
The woman was not hurt, but those who saw the shove became enraged, and two fellow officers immediately pushed Pohorence away from the scene. Soon afterward, police fired tear gas to break up the crowd.
Fort Lauderdale Mayor Dean Trantalis said he is "offended" by Pohorence's actions.
"I thought that was something that should have never happened," the mayor said. The Fort Lauderdale police union has not commented.
Also Monday, the state's attorney's office in Fort Lauderdale fired a prosecutor who called protesters "animals" in a Facebook post.
The Florida State Attorney's Office said prosecutor Amy Bloom's remarks were "entirely inconsistent with its ideals and principles."
Bloom said she was referring to all demonstrators, regardless of race. She said she deleted her post within seconds, but not before someone read and reported it.