Avenatti's clients have included Julie Swetnick, who accused Brett Kavanaugh of aggressive sexual behaviour before his confirmation to the U.S. Supreme Court.
The alleged victim in the case had visible injuries, according to Officer Tony Im, a police spokesman.
Avenatti says in a statement released by his law firm Wednesday that the accusations were "fabricated and meant to do harm to my reputation".
The lawyer had been stumping around the country as he pondered a presidential run in 2020.
In a statement, Avenatti called the allegations "completely bogus".
According to the report, the woman was seen running out of a high-end apartment complex in Century City, which is in Los Angeles, California, on Wednesday.
"They had no option in light of the allegations", Avenatti said.
TMZ reporter that Michael Avenatti was arrested on domestic violence charges Wednesday. He has NEVER been abusive to me or anyone else.
Avenatti has made himself a almost household name through his relentless media presence as he represents adult-film star Stormy Daniels in two lawsuits against Trump.
The unnamed woman was seen Wednesday running out of the apartment and screaming into her cell phone while wearing sunglasses to hide the alleged bruises on her face.
She says not only was she not injured and not at his apartment, she has never known him to be physically violent. He said he will be "fully exonerated".
Milano and Avenatti appeared together for a protest against President Trump outside The White House in July.
The Vermont Democratic Party canceled events planned for Friday and Saturday, where Avenatti was scheduled to speak, and is refunding ticket sales.