Corey Logan Sealey admitted the offence and was also ordered to pay £125 prosecution costs.
Prosecuting advocate Roger Kane told the court that the victim in the case was at the Station Road pub in Port Erin on April 30, at 8.30pm.
He saw 18-year-old Sealey and another male, sitting a couple of tables away.
They were described as ‘play fighting’ and the victim said he then jokingly told one of them: ‘He’d knock you out.’
This angered Sealey, who then approached the victim and punched him.
He was removed by staff and later arrested.
During a police interview, Sealey, who lives at Marashen Crescent in Port Erin, admitted punching the male, saying that he had been annoyed by his remarks and had wanted to ‘shut him up’.
Mr Kane said that, although no injury had been caused, it had been an unprovoked, gratuitous act of violence in a public house.
Defence advocate Kaitlyn Shimmin asked the court to deal with the offence by way of a financial penalty.
Ms Shimmin asked for credit to be given for her client’s guilty plea and the fact that it was his first conviction.
The advocate said that Sealey had made admissions to the police and was remorseful for his actions.
Ms Shimmin went on to say that the defendant wanted to apologise to the complainant and the pub staff.
Magistrates ordered him to pay the fine and costs at a rate of £50 per week.