Quarantine-free travel between from New South Wales to New Zealand will be paused for at least the next 72 hours from 11:59pm.
Covid-19 Minister Chris Hipkins said the pause will be under "constant review" as the source of infection in Sydney is investigated.
He said the Government was taking a "precautionary approach" and will review the decision on Thursday.
A public health assessment today determined the overall risk to public health in New Zealand remains "low".
"There are still several unknowns, including a case that was infectious while in the Sydney community and a primary school age child with no clear link established at present," Hipkins said.
Three flights are due to arrive tonight at Auckland Airport before the 11.59pm cutoff.
There have now been 21 cases of community Covid-19 transmission reported in Sydney over the past week alone. Other Australian states are implementing restrictions on visitors from NSW or banning visitors from exposure sites.
More than 6000 people were contacted by contact tracers last week after arriving in New Zealand from NSW before last Wednesday, when the state’s first community infection was announced.
So far, 16 people locally have been identified as having visited locations of interest in Sydney.
“The majority of these contacts self-identified through Healthline and have been provided appropriate health advice to stay home and get tested,” the Ministry of Health said this afternoon.
Five of the group have been made to self-isolate for 14 days, having to test negative twice during that period. The remaining 11 tested had to self-isolate until returning a negative day five test.
Tonight, the Ministry of Health said anyone who was at Westfield Bondi Junction mall, including its carpark, any time between June 12 and 18 should contact Healthline. These people should get tested and stay at home until a negative test result, or until instructed.
A full list of locations and times of interest is on the NSW Health website.
Anyone who has only been in Norfolk Island and not in NSW is still eligible for quarantine-free travel.
Meanwhile, quarantine-free between New Zealand and Victoria will resume from 11.59pm today.