Michael, 50, had originally been arrested for three domestic violence felonies – preventing the report of the victimisation, false imprisonment and inflicting corporal injury on a cohabitant - but Los Angeles District Attorney’s office decided not to pursue those charges.
District Attorney’s spokesperson Shiara Davila-Morales said: "Evidence was found to be substantiated to one misdemeanour count."
If convicted of the offence, Michael – who is the father of troubled actress Lindsay Lohan – could face up to a year in jail.
Prosecutors are expected to recommend a $30,000 bail be imposed at arraignment.
He denied the accusations, accusing Kate of lying, faking her injuries and attacking him.
He said: "I didn't touch her. I didn't do a damn thing to her.
"When we got back to the house, she was in the bedroom and I was cooking dinner when she started screaming. She was yelling 'What the f**k is this? You're a piece of s**t. Who is Maryann Mancuso?' and that is a friend of mine.
"She was holding my phone and I grabbed it away from her. She had something sharp in her hand and she grabbed my arm and slashed my arm open.
"I told her to get out of here, you get your stuff and get out of here right now.
"She said I gave her a fat lip, she has Restylane in her lips.
"This was all a set up."