UFC's McGregor says in tweet that he's retiring

Helwani not totally sold on McGregor's retirement announcement (1:04)

Ariel Helwani reacts to Conor McGregor's sudden retirement announcement and explains why it feels very spur-of-the-moment. (1:04)

UFC star Conor McGregor announced his unexpected retirement from mixed martial arts in a post on social media in the early hours of Tuesday.

The announcement came just hours after McGregor, 30, told "The Tonight Show Starring Jimmy Fallon" in a pre-taped interview that he and the UFC were negotiating a potential return to the Octagon in July.

"We're in talks for July," McGregor said in his Tonight Show appearance. "We'll see what happens, a lot of politics going on. The fight game is a mad game. But like I said, to my fans, I am in shape and I am ready.

"I have done my piece for the company. I don't necessarily need to fight. I am set for life. My family is set for life. We are good, but I am eager to fight. So, we'll see what happens. I'm staying ready."

UFC president Dana White told ESPN that McGregor's retirement "totally makes sense." White also said he believes the announcement is legitimate.

"He has the money to retire, and his [Proper 12] whiskey is KILLIN it," White said via text message. "It totally makes sense. If I was him, I would retire too. He's retiring from fighting. Not from working. The whiskey will keep him busy, and I'm sure he has other things he's working on.

"He has been so fun to watch!!! He has accomplished incredible things in this sport. I am so happy for him, and I look forward to seeing him be as successful outside of the Octagon as he was in it."

McGregor (21-4) has "retired" on social media before. In April 2016, he announced on Twitter, "I have decided to retire young. Thanks for the cheese. Catch ya's later."

At that time, McGregor and the UFC were in negotiations regarding a potential fight at UFC 200. McGregor ultimately did not fight at UFC 200, but he appeared in the Octagon one month later in a highly profitable second fight against his rival Nate Diaz.

McGregor's representatives did not immediately respond to a request for comment.