McGregor said last week that he was quitting mixed martial arts, but Nurmagomedov, who beat the Irish fighter for the UFC lightweight title in October, isn't buying it.
Speaking Tuesday in his native Russia at a Moscow university, Nurmagomedov said that McGregor "couldn't reach a deal with the UFC, and it's so they feel they've lost him and they could lose money.
"I don't think he's finished,'' Nurmagomedov added.
McGregor previously retired in April 2016 but reversed the decision two days later and returned to the UFC. The 30-year-old Irishman hasn't won a fight since beating Eddie Alvarez in November 2016 to become the first UFC fighter to hold championship belts in two divisions at once.
UFC president Dana White concurred with Nurmagomedov.
"No," White said Sunday in an interview with KLAS-TV, when asked if he believed that McGregor was truly retired. "I think that there's some things that Conor wants and I think that Conor wants to get together face to face, he and I, and we probably will in the next couple of weeks and we'll get this thing figured out."
"Listen, who gets respected more than Conor McGregor does? Come on," White said. "The guy's never been disrespected, definitely not by me. And he's got a lot of money too.
"But he's stuck on this thing where he wants a piece of the ownership and that's just -- if you look at basketball, Michael Jordan didn't own a piece of the league, and the list goes on and on. Is Conor very valuable to the sport and to the brand, the UFC? Of course he is. That's a tough one, but I think there's other ways that we can make him happy."
Nurmagomedov also said that he would like to fight again in September, two months after the end of his Nevada State Athletic Commission ban for the chaotic brawl with McGregor's team after the October fight. McGregor's sanction ends Saturday.
However, Nurmagomedov said he didn't want to fight before longer sanctions on two other Russian fighters also end. Abubakar Nurmagomedov and Zubaira Tukhugov were each banned for one year by the Nevada State Athletic Commission for their part in the brawl. Those sanctions run until Oct. 6.
"They were banned because of me,'' Nurmagomedov said.
ESPN's Michael Rothstein and The Associated Press contributed to this report.