The new discoveries were in spite of the closure of international borders against foreigners, and returning New Zealanders put in mandatory quarantine.
The government has said the source of the new infections was unknown so far.
Long queues were reported outside supermarkets in Auckland and across other parts of the country, as people raced to stock up on food and other essential items before the new restrictions took effect from noon.
New Zealand’s biggest city will move back into alert level-3 lockdown, which would mean people should stay away from work and school.
Gatherings of more than 10 people would again be restricted.
The restrictions will be in effect for three days, until Friday.
The rest of New Zealand will move into level 2, meaning social distancing measures would be applied and mass gatherings would be limited to 100 people.
Health Minister, Chris Hipkins, told Radio New Zealand on Wednesday that the government was considering making mask-wearing mandatory for Aucklanders.
New Zealand’s successful fight against COVID-19 was hailed globally and the Pacific island nation of five million was seen as one of the safest places, as the pandemic raged globally.
It marked 100 days without a domestic transmission of the coronavirus on Sunday but warned against complacency as countries like Vietnam and Australia, which once had the virus under control, now battle resurgences.
Calls have grown to postpone the national election scheduled for Sept. 19 as political parties suspended campaigns due to the new restrictions.
“It’s going to be very difficult to have an election in mid-September when we are now mid-August,’’ opposition National Party leader, Judith Collins, told Newshub.
Ardern, who is seen winning comfortably, according to opinion polls, has said she has not yet considered the impact of the new restrictions on the polls.