Boxing sensation Claressa Shields will have to find another male challenger to fight -- because Shawn Porter says he's NOT down to get in the ring with the female superstar.
Porter appeared on the "TMZ Sports" TV show after Shields told us this week she's 100% confident she could BEAT top male fighters like Porter, Keith Thurman and Gennady Golovkin.
So, we asked Porter for his reaction -- to which he smiled and replied, "It's cute!