Robert Pattinson SHOVES Security Guard [Video]

Robert Pattinson violently SHOVED a guy he apparently thought was a snap-happy photog while exiting a club Friday night ... but turns out it was a security guard.

In the chaotic video -- taken outside the Troubador -- a boozed-up looking Robert is seen trying to leave the venue while swarmed by paps. You can tell it's tough to navigate.

As Robert makes his way to his car through the mayhem, he suddenly throws his hand to another guy's face ... forcefully PUSHING him backwards. Suddenly paps are heard asking, "Why'd you hit him?"

Afterwards, the vic -- who is actually part of the bar's security team -- is heard saying "He grabbed me on my face" as he picks his glasses up from the ground.

He also makes it clear Robert thought he was someone else -- a photog.