UFC fighter Brad Tavares is doubling down on his weekend call-out of Michael Bisping ... telling TMZ Sports the ex-champ is ducking him 'cause he's terrified of getting THRASHED.
"I think he’s scared ... scared to get his ass beat," Tavares said. "What else could it be?"
FYI, the Hawaiian went looking for Bisping backstage after he merked Krzysztof Jotko at UFC on FOX 29 ... to call out the UFC legend for his retirement fight.
Bisping LOL'd at Tavares' challenge -- telling the top-10 middleweight to "get the f**k out!"
But, Brad ain't giving up -- saying there's no better option for him unless he's gunnin' for Conor McGregor (yeah ... ain't gon' happen).
That said, Tavares is also down to scrap with another up-and-coming star ... and says he'll "expose him" if he gets the chance!