Mayweather fought McGregor on 26 August in one of the biggest fights in combat sports history with both fighters earning nine figures, despite the obvious mismatch in their abilities.
While the Irishman lost to Mayweather via stoppage in the 10th round, he was praised for reaching that far against arguably the greatest boxer of all time.
However, the end for McGregor was approaching from the 9th round onwards as the UFC lightweight champion was heavily fatigued as "Money" kept pressing and landing shots to his head.
When asked if he would have preferred to won via a clean knockout, Mayweather responded, stating that any more strikes could have been very damaging for the 29-year-old.
"He has a career," Mayweather said on the Hollywood Unlocked podcast, as quoted on MMAMania. "You know, he still has a career. He's still young."
"[It would be] very, very damaging. We have to think about these fighters. Even, like, my uncle Roger. Right now, I just got a call, just before I came here, he keep walking off, wandering off. No one can find him. He end up in a hospital. So, brain damage – it happens. It happens."
It is not the first time that brain damage has been mentioned with McGregor following the big August fight.
Former ringside physician Darragh O'Carroll, MD claimed a couple of days after the fight that McGregor was exhibiting signs of traumatic brain injury during the 10th round.
"[Referee] Byrd's calculation to call a stoppage was likely not based on signs of fatigue, but rather signs of traumatic brain injury," O'Carroll wrote. "Ataxia, or dizziness and loss of balance, is one of the hallmarks of concussion, a type of mild traumatic brain injury."
"Fatigue may cause sluggish and slow movements, but does not cause the imbalance and poor coordination exhibited by McGregor in the 10th round. Being wobbly, in the setting of pugilistic trauma, will always be treated as the result of head trauma and not as fatigue."