Phillip Edward Humes pleaded guilty to assault occasioning bodily harm.
Police prosecutor Ser-geant Rod Murray said Humes was on the Mandurah foreshore on January 7 at 4pm and got into an argument with his cousin.
Sgt Murray said a Jesus Christ Latter Day Saints pastoral elder came over and tried to calm them down. He said Humes punched the elder in the face, which knocked a tooth out. The victim was taken to Peel Health Campus.
Duty lawyer Clare Hay said Humes was remorseful and had apologised after the incident. She said Humes was willing to participate in victim mediation.
The court was told Humes had been placed on a community based order for a previous assault conviction. Ms Hay said Humes had been participating in anger and alcohol counselling.