Georges St. Pierre says he will announce his retirement when he is ready and adds that he's not interested in fighting Nate Diaz. (1:55)

LAS VEGAS -- If two-weight UFC champion Georges St-Pierre wishes to challenge Khabib Nurmagomedov for an unprecedented third title, he'll need to go through a contender first.

That's according to UFC president Dana White, who says the promotion has no interest in booking St-Pierre (26-2), arguably the greatest fighter of all time, against its undefeated 155-pound champion -- despite recent comments by St-Pierre.

"How does Georges St-Pierre jump over all the guys fighting in that division to face Khabib?" White told ESPN. "Just because all of a sudden he wants to come out and fight this guy -- he doesn't get to do that. If Georges St-Pierre is serious, listen, I'll give you a fight with one of these guys in the top five. If you win, you'll be in position for a title shot.

"We don't even know if Georges St-Pierre can make 155 pounds. You know what I mean?"

St-Pierre, 37, is the longest-reigning welterweight champion in UFC history. He vacated his 170-pound title in late 2013, then returned last November from a four-year absence to defeat Michael Bisping for the 185-pound middleweight title.

The Canadian star immediately vacated that title as well, citing a medical condition brought on by the weight gain. In a recent interview on ESPN's Ariel Helwani Show, St-Pierre said he has not officially retired but is likely only interested in one fight.

"The thing that excites me the most is when I could be the first to do something," St-Pierre said. "When something cannot be done and people doubt me. (Nurmagomedov) is a great champion and, in terms of legacy, I can't think of a better fighter right now who has a better legacy than Khabib."

Nurmagomedov, of Dagestan, has expressed interest in fighting St-Pierre in the past. His manager, Ali Abdelaziz, told ESPN he doesn't think the UFC would agree to making that fight for Nurmagomedov's title but suggested that a non-title, catchweight fight might be possible.

Earlier this year, the UFC discussed a potential lightweight bout between St-Pierre and Nate Diaz, but the fight was never booked. St-Pierre has since said he has no interest in fighting Diaz.

St-Pierre has never fought at 155 pounds. He told ESPN he weighed 183 pounds earlier this week and expressed confidence he could drop to 155.