Jacinda Ardern says people not following Covid-19 rules and regulations has created a number of "high-risk" situations.
"People who should have been in isolation, weren't," she said, as Auckland was plunged back into lockdown following another Covid-19 case in the community, linked to the Papatoetoe cluster.
How the 21-year-old man got infected is yet to be confirmed, adding to concerns surrounding the infection, as is the number of places they have visited while infectious.
The Prime Minister said people make mistakes and NZ won't succeed if "we turn on one another".
"We cannot exist in an environment where we set rules and they [are] breached consistently," she added, however.
This latest case visited the GP for a test yesterday, and then went to the gym.
A case revealed yesterday worked a shift at a KFC while they should have been isolating.
Auckland will move to Alert Level 3 restrictions from 6am tomorrow morning, while the rest of the country will return to Alert Level 2 restrictions.