We talked to the 32-year-old UFC star as he was leaving T-Mobile Arena following his trilogy fight victory over McGregor ... and we asked if Dustin was interested in a 4th fight.

"Anything is possible. I just have to get with my family, and see what's next."

Of course, Conor -- who underwent a successful 3.5-hour surgery yesterday to repair his broken leg -- is facing a long and arduous rehab process... and that must happen before a 4th fight is made.

Speaking of Conor's injury... we also asked Poirier if he felt bad for McGregor.

"You never wanna see someone injured like that. The recovery is gonna be hard and losing."

But Conor is adamant his fighting career is nowhere near done ... he says he will be back -- and sooner rather than later.

Does Dana White have interest in a 4th fight? 'Cause without the UFC honcho on board, it ain't happening.

White was asked about the possibility of a rematch Saturday night ... and Dana certainly didn't say no.

"Dustin Poirier will fight for the title and when Conor is healed and ready to go, we'll do the rematch."