"I would like to rematch him under boxing rules, again," McGregor told Robbins.
"I believe I would win. Actually, there I go again with that fake humbleness, I know I would win!"
The first meeting was stopped in the 10th round by the referee after Mayweather had McGregor on the ropes.
McGregor held his own early in the fight, but eventually the stamina and endurance of Mayweather paid off as he wore out his opponent.
"The approach caught me off guard. I was not prepared for it, I was not used to it," McGregor said.
Mayweather walked away from the ring after he made a one-fight comeback in 2017, ending his professional career with a perfect 50-0 mark.
McGregor announced his retirement from the UFC in late March.
Despite retiring, McGregor maintains he can outbox the undefeated Mayweather.
"He never fought like that in his entire career, but he was forced to fight that way because he was getting beaten," McGregor said.