"She was shocked but otherwise unharmed," police said.
The man was arrested for common assault but let off with a pre-charge warning.
"He said he was extremely remorseful for what happened," the police spokesman said.
Paul Donaghy was on the flight and told the Herald he had "restrained [the] guy".
When the pushing began, he put the elderly man in a "bear-hug".
"He wasn't a big guy, he was just very agitated," he told Fairfax.
"His wife was further down the plane so she couldn't do anything. I just thought 'I can help somehow' and that was how."
Donaghy described the flight attendants as "too distraught to keep working".
Police said the stoush caused the flight to be delayed. Queenstown Airport said on Twitter that it had been cancelled.
A passenger on the flight, Steve Warne told the Herald he did not see the event that caused everyone to disembark the plane.
"What I find absolutely remarkable is the inconvenience and upset that this man caused to so many - and yet he is let off with a warning.
"There were those passengers panicking because they were missing connecting international flights, people with upset children and just people like myself who had been working in the town and wanted to get home to their families. This man's actions caused a raft of upset and he gets a mere warning?"
Warne said the man should have to foot a good share of the cost of the debacle.
"I think then, that he would think twice about pushing anyone else around in the future."
An Air NZ spokeswoman said police have confirmed there was an alleged assault on board the plane in Queenstown.
The incident happened as customers were boarding the flight.
Air NZ said customers are being reaccomodated on alternative services.
Some passengers have already caught different flights, while others will be staying in Queenstown overnight before flying out tomorrow.
