The two stars were each walking the red carpet for the VMAs when, according to photos captured by photographers covering the event, it appears that they got into a bit of a scuffle. In one photo, McGregor, who wore a pink blazer and black pants for his appearance, is seen being held back by a member of his team as he attempts to swing at the musician.
According to sources close to TMZ, McGregor asked Machine Gun Kelly (MGK) for a photo when the two crossed paths, to which the musician declined. That's when, according to the sources, the situation allegedly "escalated into him pushing Conor," who may have stumbled back and spilled his drink.
The outlet also reports that their respective teams were able to step in before things truly escalated between the boxer and the rapper.
Get South Florida local news, weather forecasts and entertainment stories to your inbox. Sign up for NBC South Florida newsletters.
A video shared on Twitter by user @g0ddessmez shows what seems to be both McGregor and MGK exchanging words before being separated by members of their teams.
Fox, who accompanied her other half for his appearance on the red carpet, was also seen in the midst of the quick melee in videos shared on social media.
Photos: Top Moments From MTV's 2021 Video Music Awards
Asked by "Entertainment Tonight" what led to the scuffle, McGregor told the outlet that "absolutely nothing" happened and he doesn't fight "little vanilla boy rappers."
"Nothing happened with me, I only fight real fighters, people that actually fight, you know what I mean," he continued. "I certainly don't fight little vanilla boy rappers. I don't even know the guy. I don't know anything about him, except that he's with Megan Fox."
The alleged scuffle between the two comes almost two months after the boxer suffered from a broken tibia (also known as the shinbone) in his left leg, which is why during Sunday's events, a walking cane was reportedly tossed to the ground before it was given back to the injured athlete.
A rep for Conor tells E! News, "It was unfortunate that MGK's security reacted. Conor and Dee enjoyed the performances."
E! News has reached to MGK's reps for comment and has not heard back.