Auckland is entering COVID-19 alert level 3 from midday Wednesday for three days.
It comes after four cases of the virus were found in Auckland's community on Tuesday.
Prime Minister Jacinda Ardern says it's important to take a "precautionary approach".
"At this stage, we have not yet been able to determine the source of these cases."
The rest of New Zealand is entering alert level 2 from midday Wednesday for three days.
"As disruptive as it is, a strong and rapid health response remains the best long-term economic response."
The area defined as Auckland and under level 3 restrictions is "the geographic boundary of the Auckland super city", which extends from Wellsford in the north to Pukekohe in the south.
What Auckland's level 3 restrictions mean:
- people need to stay at home in their bubble, other than essential movements such as going to the supermarket or local recreation
- Aucklanders need to work from home unless they are essential workers
- all schools and childcare facilities will close as of Wednesday morning, except for the children of essential service workers
- all bars, restaurants and businesses must close by midday Wednesday
- gatherings of more than 10 people are restricted, and are also restricted for funerals, tangi and weddings
- travel into Auckland is prohibited unless you normally live there and are travelling home
- Ardern also asks Aucklanders to wear masks while accessing essential services
What level 2 restrictions mean for the rest of New Zealand:
- social distancing of two metres applies
- mass gatherings are limited to 100 people
- businesses can open if they follow physical distancing and record-keeping guidelines
- hospitality businesses must keep groups of customers separated, seated and served by a single person
- schools, early learning services and tertiary institutes are open
- Ardern says masks can be worn if someone is in a place where social distancing is difficult, for example, on public transport
Ardern says New Zealanders know what to do since the country has successfully done it before.
"Please stay home if you're in Auckland, be vigilant, we will get through this."
She says if the source of the four new community cases isn't identified, what should be identified is whether there is wider geographic spread of the virus.
Director-General of Health Dr Ashley Bloomfield says there will be no barriers to anyone with cold and flu symptoms from getting a test.
"I've said it previously, but it's even more relevant now, if you are offered a test, please take it."
He adds anyone that's identified as a close contact of the cases will be contacted by the contact tracing team.
"Please be responsive if you are contacted - return the call.
"This case is a wake-up call against any complacency that may have set in."