Colm Mee, who is 26 and from Cloverhill, paid €400 to St Vincent de Paul after telling Judge Paul Kelly that he was “extremely sorry” for his actions.
Letterkenny District Court heard Mee was among a group of people wrestling on the ground around 11.35pm.
There were a large number of incidents in the town at the time with gardaí dealing with them.
Defence solicitor Patsy Gallagher said his client had come to Donegal for the rally and had too much to drink.
He said a row began over accents and football and Mee, who works as a security door fitter, got involved.
Judge Kelly heard that Mee was aggressive towards gardaí but that he had calmed down once he had arrives at Letterkenny Garda station.
He had later apologised to gardaí for his actions.
Mee told the judge he was sorry, adding: “It is totally out or character. It won’t happen again.”
Judge Kelly said gardai had enough to be doing “without putting up with this sort of abuse.”
Mee was sent to St Vincent de Paul in Letterkenny and ordered to return with a receipt for a donation of €400.
Judge Kelly applied the Probation Act.