Liev Schreiber -- Breaks Up Pap Fight w/ Cannibal Waiter

Liev Schreiber ended up playing mediator between a photog and a waiter who had originally come to HIS defense ... after the waiter repeatedly threatened to EAT THE PHOTOGRAPHER!!!

It all went down at Giorgio Baldi in Santa Monica over the weekend. As Schreiber was hounded by photogs (none of which work for TMZ), a waiter came to his aid and tried to shoo them away. But things got physical with one of the photogs (a female, no less) and she swung the camera at the waiter in defense.

That's when the waiter went all Jeffrey Dahmer, screaming, "You touch me with that and I will EAT YOU ALIVE! You understand? I will eat you! EAT YOU!" Clearly the restaurant does not feed its staff.

Before things could really get out of hand, Liev came over to play peacemaker and calm things down ... and in the end no one got eaten.