Dana White absolutely UNLEASHED on the guy suing Michael Bisping for allegedly attacking him at the gym ... saying the dude is a "f**king p**sy" who talked trash and couldn't back it up.
The UFC honcho still hasn't talked to Bisping about the incident, but says he's pretty sure he knows how it went down.
"I’m sure it’s that typical f**king p**sy who opens his mouth at the f**king gym, and then Bisping goes over and -- I don’t know what Bisping did to him, but now he wants to f**king sue Bisping -- should have shut your f**king face in the first place."
"You’re a clown. Guys like that are a f**king embarrassment," White said on the RQMS Podcast.
TMZ Sports broke the story ... a man claims Bisping went nuclear on him for "taking his weights" at a 24 Hour Fitness in Anaheim back in July -- choking him and almost causing him to lose consciousness.
Now, he's suing the middleweight champ for assault, battery, intentional infliction of emotional distress and more.
Bisping responded to the allegations on Thursday, saying they are "completely inaccurate."