"I would like to rematch him under boxing rules, again," McGregor said to Tony Robbins during a recent interview ... "and I believe I would win."

"Actually, there I go again with that fake humbleness ... I KNOW I WOULD WIN!"

Yeah, you can hear it in his voice ... McGregor really wants this.

Of course, Conor first fought Floyd back in August 2017 -- with Floyd beating on Conor so badly in the 10th round, the referee stopped the fight.

But, Conor didn't see the bout as a one-sided massacre ... he thinks he was WINNING early on.

"When I went into the fight in the early rounds I was WHOOPING him in the early rounds," Conor said ... "I went back to my corner after the 1st round and I said, 'This is easy!'"

But, Conor says Floyd switched up his style -- going from a "back-footed," defensive approach to a more aggressive "Mexican style."

Conor says the switch shows how talented Floyd is ... but now Conor says he can prepare better for that alternative style and crush Floyd in a rematch.

"He never fought like that in his entire career, but he was forced to fight that way because he was getting beaten," Conor said.

"The approach caught me off guard. I was not prepared for it, I was not used to it ... and he walked me down and end up getting the stoppage."

Conor says Floyd originally agreed to fight McGregor in an MMA match after the boxing event -- but Conor says, "I haven't heard from him since!"

Floyd has been taking exhibition fights ever since racking up his 50th pro victory ... but will a rematch with Conor pique his interest in a comeback?