Justin Bieber -- Attacked at Nightclub

Justin Bieber was bum rushed in a Canadian nightclub by an over eager partier who tried in vain to tackle him -- and TMZ has the pics.

It all went down at 3 am today at a Toronto nightclub. Sources on scene tell us JB left his safe VIP section to mingle with the regular folk -- and that's when a male clubgoer charged at him, got hold of his shirt (which he was wearing) and attempted to take him down, but failed.

Which makes sense ... have you seen Bieber's abs? Of course you have.

In the pics ... you can see security rushed in stat (below) and managed to pull the guy off Bieber -- successfully taking him to the ground. In the midst of the chaos we're told JB was seen trying to defend himself, unleashing a fury of kicks.

The attacker was escorted out of the club. Police were never called.