Khabib Nurmagomedov defeated McGregor at the UFC 229 competition by way of a submission hold, but the end of the fight was marred by an ugly brawl where punches were thrown by both camps.
It's unclear exactly what happened, but during the brawl McGregor was hit by members of Nurmagomedov's camp.
McGregor has decided not to press any charges, but UFC authorities have withheld Nurmagomedov's $US2 million prize and are considering sanctions like kicking him out of the UFC.
Nurmagomedov - the undefeated lightweight champion - posted a message on his Instagram page early this morning, New Zealand time, saying he no longer wanted the prize money.
Taking aim at the UFC itself, he asked "why didn't you fire anyone when their team attacked the bus and injured a couple of people?
"They could have killed someone there, why no one says anything about insulting my homeland, religion, nation, family?"
The comments relate to an incident during the lead-up to the McGregor fight where McGregor threw a heavy metal dolly at Nurmagomedov's tour bus.
The dolly shattered glass, which causes facial injuries to two of Khabib's team.
"Why do you have to punish my team, when both teams fought ... if you say that I started it, then I do not agree, I finished what he had started.
"In any case, punish me, [team mate Zubaira Tukhugov] has nothing to do with that ... if you think that I’ll keep silent then you are mistaken.
"You cancelled Zubaira’s fight and you want to dismiss him just because he hit Conor ... but don’t forget that it was Conor who had hit my another Brother FIRST, just check the video.
"If you decide to fire him, you should know that you’ll lose me too. We never give up on our brothers in Russia and I will go to the end for my Brother.
"If you still decide to fire him, don’t forget to send me my broken contract, otherwise I'll break it myself.
"And one more thing, you can keep my money that you are withholding ... you are pretty busy with that, I hope it won’t get stuck in your throat.
"We have defended our honor and this is the most important thing. We intend to go to the end."
The message also seemed to unofficially confirm that UFC had cancelled Tukhugov's upcoming bout against Artem Lobov - a team mate of McGregor.