Freddie Roach Shuts Down Pacquiao vs. McGregor, 'It's Not True'

Manny Pacquaio's team is publicly shutting down any talks of a Conor McGregor boxing match -- with Pacman's trainer Freddie Roach telling TMZ Sports it just ain't happening.

Freddie told us he's personally spoken to Bob Arum (Manny's promoter) -- who'd have to sign off on the match along with Dana White -- and Bob shot down the rumors.

"I talked to Arum and Arum says it's not true," Roach said outside Craig's in L.A.

Freddie did tell us the 1 guy he'd like to see Pacquiao scrap with ... and also DESTROYED Manny's old rival, Floyd Mayweather, for even considering a UFC fight.

"He's gonna get his ass kicked ... he's a f**kin' old man."

FYI, Conor told us he wants to return to MMA last week.