The scenes at Parliament are "extreme and violent" the Prime Minister said, after tensions erupted as tents were lit on fire, bricks thrown at police and LPG bottles thrown on flames.
Chaos and violence erupted at Parliament as police moved to remove protesters from the grounds on the 23rd day of the occupation that saw hundreds camped out on the front lawn.
Tents were lit on fire, with gas canisters creating loud explosions. Police have been injured.
"There are words I cannot use in this environment from what I saw today," Jacinda Ardern said.
"It is still a live event."
She said she was "angry and also deeply saddened" as she watched the Parliament children's playground "destroyed".
Ardern said police expected "hostility, resistance and violence".
"It is another thing entirely to witness it."
She was "angry and disappointed" to see Parliament "desecrated in that way".
She had a "deep admiration and thanks" to police, fire and emergency staff.
The protest had moved into its 23rd day, she said, which had seen "wild and dangerous" spread.
"There has been foreign influence in what we have seen. In terms of disinformation sourced out of other countries."
She said New Zealand would not be defined by the actions outside Parliament.
"We will not be defined by this. Our people will not be defined by a small handful of protesters.
"I hope we remember one thing. Together thousands more lives were saved over the last two years ... than were on that front lawn today.
"That is what will define us. No protest, no fire no placards will define that."