The 72-year-old Australian actor, who plays the purple-haired character with oversized rhinestone eyeglasses, struck celebrity freelance photographer Malcolm Ladd, 54, said publicist Suzie Howie.
"I can confirm to you that Barry did hit him," Howie said. "He was obviously very upset."
"But at least he didn't throw a phone," added Howie, referring to Australia-based actor Russell Crowe, who was given a conditional discharge by a New York court last year after pleading guilty to throwing a phone at a hotel receptionist.
Humphries became upset when Ladd followed him from Dee Bee's Cafe in Sydney's exclusive Double Bay, where the actor had lunch Wednesday with musical director Andrew Ross, Howie said.
New South Wales state police had not received a complaint about the punch, a police spokeswoman said on customary condition of anonymity.
Ladd's photos of Humphries at lunch appeared in early editions of News Corp. newspapers in Australia on Thursday.
He told News Corp. that Humphries punched his face as he tried to take a close shot outside the restaurant.
"It knocked my glasses off. It was a good punch — it still hurts," Ladd was quoted as saying. "It's the first time I've been attacked and I've photographed just about everyone before."