Mayweather was at a press conference to promote his upcoming boxing match against Logan Paul when the younger Paul brother snatched the 44-year-old’s cap to spark mayhem back stage.
The boxing legend has long-claimed his real fighting days are behind him, with many seeing his exhibition bout against Logan as a laughable sideshow.
McGregor fought Mayweather in his own exhibition fight in 2017, with the American winning by a stoppage in round 10 of the bout.
And the Irishman has now slammed Mayweather for the altercation with the younger Paul on Thursday.
“Hey Leonard Ellerbe, what the f*** is Floyd at?” McGregor wrote in a post on Instagram, in which he tagged Mayweather’s long-time business partner.
“The kid curled up, didn’t fight back once, and Floyd is still running around acting the tough guy.
“The kid actually just pulled this shambles of a situation Floyd is in out of the drain for him. He should thank him. It’s embarrassing!”
McGregor also blasted Mayweather for choosing to fight Paul, rather than take on a legitimate professional boxer, and suggested he will earn less money as a result.
“Pro to pro it’s embarrassing. He will not scratch $10 [million] for this fight and he knows it,” ‘The Notorious wrote.
“It was cancelled once already. The world is watching this on Twitter. He’d fight a half decent pro and command $20 [million] upwards, yet it’s this s***.
“Whatever way you spin this, it’s sad. Fight someone for real, on your record, or f*ck off mate. Slap head!”
Mayweather’s bout with Logan is set to take place in early June, with McGregor facing Dustin Poirier in the final fight of their trilogy later in the summer.