Nicholas Skutela broke the jaw of a man in a Watford night club after accusing him of "grassing" his group to door staff.
He confronted victim Jake Emberton in the smoking area at Area nightclub and accused him of staring at his friend Joe Franklin, saying that if he continued he would: "Beat the s... out of him."
Mr Emberton, who vaguely knew Mr Franklin, told the door staff who advised him to keep away from Skutela's group, St Albans Crown Court heard today.
But he ignored their advice and went over to Skutela's group to make peace.
Skutela, who had seen him talking to the bouncers, accused Emberton of being a "grass" and delivered a forceful punch to his face. He suffered a fractured jaw, which did not require surgery, but was extremely painful.
Skutela, 26, of Scottswood Road, Bushey, was convicted of causing grievous bodily harm in the club September 8, 2012. He had a previous reprimand for assault.
Defence barrister, Nicola Cafferkey gave the judge a letter from a stroke victim whose own son has died. It set out how Skutela helps the man.
She said Skutela was training to be a doorman and had suffered a knee injury when he was assaulted himself in May last year. She said he works as a labourer three days a week, earning £50 a day, and lives with his parents.
Judge Andrew Bright QC said: "This is a case that crosses the custody threshold, but I am satisfied you are a young man who has a great deal of potential."
He said the provocation for the assault had been slight, but Mr Emberton should have taken the advice of the door staff and kept away from Skutela's group.
He passed a six month jail sentence suspended for 12 months and ordered him to carry out 200 hours' unpaid work. He must also pay £1,750 compensation to Mr Emberton and £1,250 costs at the rate of £35 a week.