The nation has been placed under the highest level of Covid restrictions which include mandatory mask-wearing in shops and on public transport.
In addition, indoor hospitality settings such as bars and restaurants will be capped at 100 people.
“My wedding will not be going ahead,” Ardern told reporters, adding she was sorry to anyone caught up in a similar situation.
Ardern had not disclosed her wedding date, but it was rumoured to be imminent.
Asked how she felt about the cancellation of her wedding to longtime partner and fishing-show host Clarke Gayford, Ardern replied: "Such is life."
She added: "I am no different to, dare I say it, thousands of other New Zealanders who have had much more devastating impacts felt by the pandemic, the most gutting of which is the inability to be with a loved one sometimes when they are gravely ill.
“That will far, far outstrip any sadness I experience."
The latest curbs come after nine cases of Omicron were detected in a single family that flew to Auckland for a wedding earlier this month.
The family, who flew in from the Nelson-Marlborough region, attended a wedding and other events while in Auckland, with estimates suggesting they came into contact with “well over 100 people at these events,” Ardern said.
“That means that Omicron is now circulating in Auckland and possibly the Nelson-Marlborough region if not elsewhere,” she added.
The new restrictions will come into force at midnight local time on Sunday.
Under the rules, students in year four or above will be required to wear masks in school.
New Zealand's borders have been shut to foreigners since March 2020. The government pushed back plans for a phased reopening from mid-January to the end of February due to concerns about a potential Omicron outbreak as in neighbouring Australia.
About 94 per cent of New Zealand's population over the age of 12 is fully vaccinated and about 56 per cent of those eligible have had booster shots.