James Toney -- Shannon Briggs Is An Asshat ... Fight Me Instead, Punk!

Boxing legend James Toney is calling out Shannon Briggs -- claiming he should stop chasing Wladimir Klitschko around the world ... and fight him instead!!

The 3-time world champ was out in L.A. Friday and told us ... Briggs is wasting his time trying to lock up a fight with Wlad -- because Klitschko would beat his ass anyway.

So, his advice to Shannon ... bring your ass back to the U.S. and "come see me!"

We'll see if Shannon takes Toney up on his offer ... just as soon as he gets back from Germany.