She urged people to listen to health professionals and doctors.
As of last night, the number of confirmed measles cases in Auckland was 759, with 937 cases nationwide.
Her comments come after Starship Children's Hospital head Dr Mike Shepherd penned an open letter, outlining his "extreme concern" about the measles outbreak.
"Some children are likely to die because of complications due to measles," he said.
Associate Health Minister Julie Anne Genter told media on Friday night New Zealand was not yet at an epidemic level and would only reach that stage if the disease spread to a significant number of other regions across the country.
Speaking to media in Auckland today, Ardern said the Government would continue to give "very strong advice," when it comes to immunisations.
"Anyone who is not immunised, get immunised".
She said there has been a world-wide 300 per cent increase in the number of people who have contracted measles since last year.
"Check your status, and access immunisations that we are making as available as we can."
The Government has sent nurses to schools and doctors in an effort to increase
vaccination levels.
On Friday, the Government deployed the National Health Coordination Centre (the NHCC) to co-ordinate the response to the outbreak in Auckland and monitor the situation in the rest of New Zealand.