Khabib Nurmagomedov tells TMZ Sports Conor McGregor should be arrested and thrown behind bars for socking an elderly man in the face.
You've seen the video by now ... The Notorious uncorked a vicious straight left to the temple of a man in a Dublin pub -- all because the dude rejected a shot of Conor's whiskey.
We talked to Khabib -- who's prepping for his massive UFC 242 fight against Dustin Poirier -- and he went off on his archnemesis.
"These people, they have to go to jail. I told you, this guy have no class. No respect," Nurmagomedov tells us.
"This is very bad for sport. Some things he doing good for sport, but right now he without his mind. He lose his mind. It's crazy."
"Government have to smash him. This is my opinion. 'Cause I'm really, really mad about this video. I don't understand how you can punch old man."
This is just the latest in a string of violent incidents involving McGregor ... and The Eagle wonders what mayhem Conor could cause next.
"Today he punches, like, old guy. What's gonna happen tomorrow?"