Former pro boxing champ Kassim Ouma was arrested for battery in L.A. on Friday — after knocking out a man who was allegedly making gay advances toward him … TMZ Sports has learned. Law enforcement sources tell us … the former IBF junior middleweight champion is telling investigators … he was hanging out in Hollywood early Friday morning when he struck up a conversation with a guy he just met. Ouma says the two went back to the other man’s home for a drink … where the guy allegedly made a pass at the boxer. We’re told … Ouma claims he politely declined multiple advances … but says when he got up to leave, the guy made one final move — and Ouma shoved him away. The altercation then escalated … with Ouma allegedly knocking the guy out cold. Cops were called to the scene — where the victim was treated and transported to a nearby hospital. Ouma was ultimately arrested for felony battery causing great bodily harm.

-TMZSports.com