Andy Ruiz says he's not bothered ONE BIT by Tyson Fury calling him a "fat guy" ... telling TMZ Sports the Gypsy King is just bashing him to stay relevant!!!

Remember ... Fury made fun of AJ to our camera guy out in NYC last month ... clowning him for getting "knocked out by a fat guy!!!"

TMZSports.com

But, The Destroyer is taking the high road after the body shaming ... 'cause he says he's actually a fan of Fury ... and sees it as a sad attempt to capitalize on Andy's superstar moment.

"Tyson Fury, he wants to be relevant," Ruiz tells us. "He wants to be in the scene. I like the guy too. I'm a big fan of him. I like how he is. I like his energy."

The 29-year-old says he's not gonna let Fury distract him from his rematch with AJ in Saudi Arabia -- aka the "Clash on the Dunes" -- but once he's done with Joshua again, THEN they can settle it in the ring.

"I don't wanna look past Anthony Joshua. I want to win on December 7th, then maybe me and him can get in a fight too."