His assailant, 35-year-old Ronan Lunney, of Foxhill Close, Enniskillen, admitted carrying out the attack, assaulting a police officer, who arrived at the scene, and being disorderly.
Lunney was given a Combination Order of 100 hours of community service and 18 months probation, during which he has to participate in the Think First programme.
He was also ordered to pay compensation of £300 to the injured party and £200 to the police officer.
A prosecutor told Fermanagh Court that at approximately 3.10am on Sunday, July 8, police found Aaron Atkinson lying unresponsive on the ground at the Johnston Bridge in Enniskillen. He and his girlfriend had been walking across the bridge with another man when Lunney shouted at him to get his arm away from the girl before punching him once to the side of the head. When the police arrived Lunney was standing about 10 feet away. He told the officers: "I ran over and punched him. He was touching the girl. Go on, f--king arrest me."
The prosecutor said Lunney struggled with one of the police officers, shouting: "F--k off you bastard. F--k off you w--ker."
The court heard that Lunney continued to shout abuse and be aggressive. He tried to bite the officer on the hand and spat twice in his face.
The prosecutor said Lunney was not known to Atkinson nor his girlfriend but the man who was with them recognised him.
Defence barrister, Miss Heather Philips, said Atkinson and his girlfriend had been out separately and met up in the town and were walking home. There was a significant altercation between them with Atkinson pushing his girlfriend. Lunney misjudged the situation and accepted he overstepped the mark. It was a single punch.
District Judge Liam McNally said the fact it was a single punch meant nothing to him as one punch can do as much damage as 10 in the particular circumstances.
Miss Philips said Lunney had not been before the court for a considerable period of time, since 2003 for an offence in 2002.
"He has certainly distanced himself from any violent behaviour," she stated.
The District Judge told Lunney this was an "unjustified and unwarranted attack" and the assault on the police officer was "particularly reprehensible, where you spat in his face".
However, he said there had been a major improvement in Lunney's criminal record and he had not committed any offences in the past 10 years.