The UFC star, talking to TMZ Sports just days after his impressive win over Jorge Masvidal at UFC 287, says he wants to apologize to the newly retired fighter ... after Durinho accused Gamebred of an ol' veteran trick, greasing his body with lotion, making him hard to take down.

"I would like to take this moment to apologize, I kind of make a couple of accusations to him after the fight. There were a lot of emotions. He was super slippery," Gilbert tells us, continuing, "But I don't want to throw nothing bad on the guy. The guy had an amazing career. Made a lot of money. BMF champ."

"Fought for the title many times. So I don't want to throw anything bad on the guy. I would love to send apology to him, to his team. I think I make a mistake making an accusation and I hope he accepts my apology."

Of course, 36-year-old Burns beat 38-year-old Masvidal by unanimous decision in the co-main event on Saturday ... but believed he could've gotten the finish, if Jorge hadn't cheated by greasing up his body, making it near impossible to take him down.

"That guy was freaking slippery. That’s an old dog, Miami trick with the lotion, because he was so slippery," Burns said after the fight.

Asked directly if he believed Jorge lathered himself up with something slippery, Gilbert didn't mince his words.

"100 percent, I do believe [he lotioned his body]. I know those old tricks. They wake up on [Saturday] and take the first shower, and they put a lot of lotion on their body," Gilbert explained, adding, "The skin absorbs the lotion, and then after three hours, you do it again, and then after you do it again, then after you do it again."

Masvifdal didn't take too kindly to the allegation ... saying instead of lotion, it was GB's "f***ing sh***y" technique.

Bottom line -- Jorge and Gilbert have respect for one another, and with the apology, it's likely whatever little beef existed has now been squashed.

We talked to Burns about much more (after 15 minutes fighting him, is Masvidal washed?) ... and how he's gearing up to prepare to be the backup for Leon Edwards vs. Colby Covington's title fight.

Burns says he'll be ready to jump in if one of the men can't fight ... and if they do make it to the Octagon, Gilbert says he wants Colby to win.

But, not because he likes him ... Burns wants to beat Covington for the title!