A paramedic has suffered severe facial injuries after being punched while attending an emergency call out in regional Victoria.

Police say an ambulance arrived at a beach in Stoney Creek, near Lorne, about 10.30pm on Thursday following a triple-zero call about an unconscious man.

When the ambulance arrived, the paramedic was flagged down by a man.

As the two were talking, another man ran up to the ambulance and punched the paramedic in the face while he was still inside the vehicle.