War Machine, whose real name is Jonathan Koppenhaver, was taken into custody Friday about 1:45 p.m. at an Extended Stay America hotel, police said.
He is being held without bond on a fugitive from justice federal charge in the Ventura County Jail, according to officials.
Koppenhaver said he was innocent on Twitter: "The cops will never give me fair play, never believe me. Still deciding what to do but at the end of the day it's all just heart breaking.”
She also alleges that Koppenhaver stabbed her several times and that he had beaten her previously before ending the relationship in May.