Dr Martin Thom, 43, had been dispatched by a 999 call handler because the only ambulance in Fraserburgh was on an emergency call.
But the GP snapped and thumped the patient twice in the head before pushing him against a wall when he believed the drunken victim was resisting his attempts to check him over.
Thom, who has worked at Saltoun Surgery in the Aberdeenshire town for 11 years, had already completed a morning and afternoon shift at the surgery when he was called out.
He was later convicted of assault at Peterhead Sheriff Court and was fined £360.
At Medical Practitioners Tribunal Service in Manchester, Thom, who lives in Ellon, near Aberdeen, faced being struck off but he was suspended for two months after he apologised for his behaviour, which he put down to stress.
Dr Thom told the hearing: “I accept I assaulted this man. I took hold of him and there was a struggle and the two of us ended up on the ground.
“I have accepted I punched him twice. I have no recollection of doing so and that remains the case.
“I saw witness reports all agreeing that I had punched him. They said what happened and had no reason to lie about it even though I couldn’t recollect it, it must have happened.
“I accepted those witnesses over my own recollection.
“At the time I thought it was a self defence I felt I acted legitimately. I accept now that I didn’t. I felt scared by the man.
“I’ve had a lot of time to think and reflect on what happened. It was myself unfortunately who ultimately became the aggressor, I assaulted the patient, my conduct was not good at all. I should have walked away if I felt scared and threatened.”
Panel chairman Michelle Codd told him: “You have been candid in your acceptance of your wrongdoing, you have apologised and have accepted full responsibility for what occurred. You have not sought to excuse what you did, which you have acknowledged was not how a doctor should behave.”
The incident occurred on May 12, 2015 after a 999 call was made saying the young man was had been spotted slumped in the street.