The 42-year-old man stood just north of the Occupy camp holding a sign that read "Occupy Somewhere Else, Not My School," according to police.
At roughly 5:30 p.m., three to five men who disagreed with the sign walked over to the man and made their feelings known.
The victim told police the men began taking verbal jabs at him and at one point used a dog to intimidate him.
At some point during the argument, police say one of the men punched the victim in the side of the head.
After the attack, the victim said all of them men ran into the Occupy camp.
Officers searched the area but didn't find any of the men. They're continuing to investigate the incident.