"He was yelling out 'come on the field, come on the field', and he came over and hit me in the stomach. I couldn't believe it."
While the young man said he didn't hear anyone around him abusing the chef's family, in a statement released on Monday, Calombaris alleges that taunts about his family sparked his aggressive reaction.
"I am really disappointed with what occurred last night," he said.
"I regret the way in which I reacted, I am disappointed that I let it get to me, and I sincerely apologise for offending anyone.
"While I am not proud of my reaction to the situation, I was offended by a spectator yelling out abusive and derogatory comments about my family."
Last month the MasterChef judge made an apology after it was revealed that his restaurant staff had been underpaid by $AUD2.6 million.
More than 18 months earlier, Australia's Fair Work Ombudsman advised Calombaris' MAdE Establishment that 162 staff in three Melbourne restaurants were being underpaid.
The blunder was put down to "historically poor processes" and Calombaris told staff he was "devastated by what had happened" and "was so sorry we have messed up and let you down".