The Scot has been accused of punching 23-year-old Joshua Gillibrand in the head three times after being subjected to taunts, knocking him to the ground.
However, a friend of Moyes told The Mirror that the ex-Everton boss did not strike his alleged victim but merely grabbed him by the lapels.
"David had a meal with two friends and afterwards, at about 9.30pm, they were both walking past a bar when two lads started giving David abuse about Manchester United," the source is quoted as saying.
"David grabbed one of them by his lapels, but didn't hit him.
"A police car happened to be parked opposite, so they were on the scene very quickly and no-one was arrested or cautioned."
Gillibrand denies hurling abuse at Moyes, insisting that he simply asked to shake the 51-year-old's hand before being set upon.
Lancashire Police are said to have questioned Moyes over the incident.