At a pre-fight press conference for that contest, Jake Paul taunted Mayweather before stealing the undefeated former champion’s hat, leading to a brawl.
Paul, who – like his brother Logan – has ventured into boxing in recent years – was left with a black eye.
“Hey Leonard Ellerbe [Mayweather Productions CEO], what the f*** is Floyd at?” McGregor wrote on Instagram in the aftermath.
“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! Pro to pro it’s embarrassing.
“He will not scratch 10m [dollars] for this fight and he knows it. It was cancelled once already. The world is watching this on Twitter. He’d fight a half decent pro and command 20m upwards, yet its this s***.
“Whatever way you spin this, it’s sad. Fight someone for real, on your record, or f*** off mate. Slap head!”
Mayweather stopped McGregor in the 10th round of their clash in August 2018. That contest was the last fight on the now 44-year-old Mayweather’s professional record, with the American then beating kickboxing star Tenshin Nasukawa in December 2018 in an exhibition bout. He has not fought since.
Logan Paul, 26, has boxed twice, drawing an amateur contest with fellow YouTuber KSI before losing the rematch – which went down as a professional bout.
Jake Paul, 24, defeated KSI’s brother Deji in an amateur fight and has since boxed three times as a professional. The American won all three contests, most recently knocking out former UFC star Ben Askren after stopping NBA player Nate Robinson last year.
Paul has recently been angling for a boxing match against McGregor, whose last MMA outing ended in a second-round knockout defeat by Dustin Poirier in January.
McGregor, who beat Poirier in the pair’s first meeting in 2014, will take on the American again in July as they round out their trilogy.