Weston told TMZ ... his dream MMA battle would be against Kimbo ... a former MMA star who switched to boxing.
Kimbo's rep, Jared Ryan Shaw, has serious questions about Weston's state of mind: "Mental stability would have had [Weston] think twice about his wishes to fight a street certified, cage tested, and boxing ring ready Kimbo Slice."
Shaw also jabbed, "Kimbo is Nic Cage famous ... and Weston's 15 minutes are up."
Tough talk aside, the rep says Kimbo's happy to fight Weston ... but only in a boxing ring.
Your move, Weston.