Mr. Mateljan said there were two possible criminal counts that Mr. Avenatti could have faced: injury to a spouse or cohabitant, which has a three-year statute of limitations, and battery, which has a one-year statute of limitations.

He said that Mr. Avenatti and his accuser, Mareli Miniutti, 24, would have separate “informal” hearings with staff members from the City Attorney’s Office at which a judge would not be present. He said those hearings had not yet been scheduled.

Mr. Avenatti celebrated the city attorney’s decision.

“I said at the time of my arrest that I would be fully exonerated and after three thorough, detailed and professional investigations by the LAPD, District Attorney and City Attorney, the truth has now come out,” he said in a text message. “The fact that there wasn’t even enough evidence to charge me, let alone convict me, demonstrates how baseless this was. The system worked.”

On Friday, Ms. Miniutti’s lawyer, Michael Bachner, expressed disbelief at the decision.

He said a representative of the City Attorney’s Office told him they believed Ms. Miniutti’s claims but had decided not to charge Mr. Avenatti because they thought a jury would not convict him. He also said that investigators from the office had declined to interview Ms. Miniutti.

“It is an outrage that this decision was made particularly since Ms. Miniutti was never interviewed by any member of the City Attorney’s Office, despite our requests, and despite the pictures of her injuries,” he said in a statement. “It is clear to us that the city attorney simply found it easier to avoid doing its job.”