Shia LaBeouf was apparently looking for a fight before he got his butt kicked early Tuesday … and we have video of what may have instigated his epic beatdown.

Watch the video … Shia appears to be talking to a guy on the street, which seems normal … but for some reason, Shia has his arms tucked inside his T-shirt.

Then, he suddenly starts shouting obscenities at the guy — an older gentleman who stays cool the whole time — and lunges forward to deliver a headbutt straight to the guy’s face!

And we’ve got new video above showing a different angle of the scene outside the bar, apparently around the time he gets manhandled in the street before police arrived, and a different view of him being treated by paramedics.

Jeffrey Damnit, a Mardi Gras attendee who was present, tells TMZ … Shia was at a place called R Bar in the French Quarter around 5 PM yesterday. According to Jeffrey, Shia accidently fell onto him while ordering a jug of water — he says Shia told him, “You f***ing push me and I’ll kick your ass.”

Jeffrey left the bar, and he says when he returned around midnight, Shia was still there … but this time the actor had been kicked out. Jeffrey alleges Shia tried to bite the bar manager, calling him “the F-word” and “chattering his teeth together.”

As we reported … police say witnesses allege Shia punched a bar staff member, left the venue, then later returned, acting even more aggressive.