UFC middleweight contender Sean Strickland says Megan Fox ripped into him over previous comments he made about her children ... claiming the actress sent him a scathing social media message that was "f***ed up" -- even by his standards.
The former champion appeared on "Verse Us With Eric Nicksick" recently, where he shared a wide range of stories ... most of which contained his usual abrasive commentary.
At one point in the episode, Strickland -- who went into graphic detail about how big of a Fox fan he is -- explained his beef with the "Jennifer's Body" star ... saying the direct message she shot at him addressed how her kids were getting bullied online after he made transphobic remarks about their wardrobe.
Strickland said Fox then defended her kids in the DM and claimed they simply wanted to look like rockstars.
Sean responded by promising to "shut the f*** up about it" and acknowledged it was wrong to bring her kids into it ... but then went in on her, saying, "You still drink blood and s***, you still do a lot of weird s***, Megan."
The 33-year-old also found time to further his issues with Fox's partner, Machine Gun Kelly ... and brought up his altercation with the musician at a Power Slap event in February -- and made comments on his painted nails, purse and what he called a "vampire trench coat."
"I'm trying to process, I'm looking into the void," he said. "And I think I just said, 'What the f***.' Like, are you a f***ing gay vampire?"
Strickland said he even thought he was going to fight MGK right then and there ... before his lady got involved.
Dana White had to address the incident after the fact ... saying, "You can’t bring Sean Strickland around any other human beings."
"You know what I mean? It has nothing to do with Machine Gun Kelly. It’s about humans."
Strickland may be a fan of Fox ... but it definitely ain't mutual.