The Irishman broke his leg and lost to Dustin Poirier earlier this month, with many criticising his attitude.
McGregor tried to kick Poirier at a press conference, before threating the 'Diamond' and his family in a furious post-fight interview and Tristar Gym head coach Firas Zahabi has had his say.
Per MMA Junkie he vented: "I was really grossed out. I don't know how you guys can be fans of this man. I respect him as a fighter. I respect his skills - I can't deny that. But the way he behaved at the press conference was just horrible."
Despite McGregor's trash talk being one of his strongest assets, this time he took it too far.
Zahabi believes the 'Notorious' being a marquee name shouldn't give him a pass to get away with anything he wants.
He continued: "If Conor McGregor has one true friend in this world... maybe he's just surrounded by people who just want his prestige and money and they just want what they can get from him.
"But if he has a single true friend in this world, that true friend is going to take him behind closed doors and tell him, 'Look, the way you're behaving - it's stupid. You're making yourself look bad. You're embarrassing us, your family, your friends.'
"It's just a humiliating way for a true martial artist, a warrior to behave.
"He's going after kids now. Now, if that was anybody else, if that was a guy on a prelim card, we would all be like, 'Kick this guy off the roster. Kick this guy out of the UFC. No, no, no.'
"But because it's Conor McGregor, you can't say that. It's Conor McGregor - he's the poster boy. He's the one who sells all the tickets. No - there's no pass for that."
McGregor is desperate to face Poirier for a fourth time and UFC president Dana White has said it is possible.
"I don't think [a fourth fight is necessary]," Mike Brown told MMAFighting.
"But who knows where they'll be when Conor gets healthy and is back in there. We'll see where he goes. He's got a journey ahead of him.
"Maybe he needs to fight somebody else and get a win or two to get back up there but he's also the biggest star in the sport.
"He's changed the game, done so much for the sport. He's the biggest star the sport has ever seen. He brings a lot of eyeballs.
"He's done a lot of great things but I think skill wise, we've got the superior fighter with Dustin."
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