"I just know him," the head coach said Thursday. "And, it's not a fit in our locker room."

Brown has been begging Arians to give him a look since his old pal, Tom Brady, signed there last week ... and it seemed like the wideout was willing to give the team a massive discount.

In fact, AB even went as far as to say he had "a lot of fun" with Arians during their time together in Pittsburgh ... and thought they could rekindle the magic in Florida.

But, Arians, speaking on Tiki Barber's "Tiki And Tierney" show this week, said AB needs to look elsewhere for a job ... 'cause the Bucs have ZERO interest.

"Yeah, it's not gonna happen," Arians said. "It's not gonna happen. There's no room. And, probably not enough money. But, it's just not gonna happen. It's not a fit here."

Of course, Brown is perhaps the most talented wide receiver in the league ... but he'd bring serious baggage to any locker room -- and that's even if the NFL allows him to play.

Remember, Brown is accused of some heinous things -- including rape and assault -- and Roger Goodell and league officials are still investigating it all.

Plus, even on the field, AB hasn't been a model citizen ... he squabbled with the Oakland Raiders over a helmet and even got in a fight the team's GM -- this just months after he essentially forced his way out of Pittsburgh.