Notorious fought the American for the third time at UFC 264 and suffered a severe leg injury while trying to get away from a punch.
This rendered him unable to continue and Poirier was adjudged the winner via doctor's stoppage.
UFC president Dana White said that there will be a fourth fight between McGregor and The Diamond once the former recovers.
However, St-Pierre is of the opinion that he should not fight Poirier. As quoted by The Sun, the Canadian said: “If he comes back, If I’m his manager, I don’t want my client to come back to fight the same guy again for the fourth time.
"Because now it seems like Dustin has his number. He need to perhaps take another fight. I think he should comeback and maybe fight Nate Diaz or someone else that has a different style than Dustin Poirier.
"Because styles make fights and I have the feeling that now Dustin Poirier probably has his number right now. Conor’s been out for a long time. He needs to get back in there to spend more time in the Octagon, in order to find his own self, the way he moves, and his ability.
"It seems like he might have lost some of his ability, due to his inactivity.”
McGregor has a knack of going personal in search of a rematch and has done so recently. The Irishman said:
"I bounced your head off the canvas like a basketball. Your wife bro. The dm’s.
"Elbows into your dome. The soft part of the skull that doesn’t harden ever. From when you’re a baby. Drilled into your skull at 100mph. U slept on my belly!”
A fourth fight between McGregor and Poirier would be one that fans would love to see but given the massive dip in the former's form, he might suffer another defeat.