She said someone would be present at the school tomorrow to advise people the service had been cancelled.
She hoped people would take time on Sunday to remember the tragic event in their own way.
The national remembrance service in Christchurch - which was to be held at Horncastle Arena in Christchurch - was expected to attract a large crowd, with many travelling from around New Zealand and from overseas.
Prime Minister Jacinda Ardern said while there was no "community transmission" of Covid-19, the Government was taking a precautionary approach.
"This is a pragmatic decision. We're very saddened to cancel, but in remembering such a terrible tragedy, we shouldn't create the risk of further harm being done.
"The advice we received for this event, is that based on people travelling from different parts of the country and from overseas if there was a case it could be difficult to trace those who had come into contact with that person, so we are taking a cautious approach.
"March 15 now becomes an opportunity for every New Zealander to reflect in their own way on the events of a year ago.
"I encourage everyone to take time on Sunday to remember and to recommit to the values of inclusion and love demonstrated so clearly a year ago."
Christchurch Mayor Lianne Dalziel said the decision was made to cancel the event given the rapidly changing environment around Covid-19.
"Tomorrow, we can still reflect on the incredible ways the community came together in response to the events of that tragic day, and think of ways that we can build on the compassion and unity that was so poignantly shown in our city, across the country and throughout the world."
Auckland's March 15 remembrance event has also been cancelled, mayor Phil Goff said.
"The decision has the support of the leaders of the Muslim community in Auckland and Government and is consistent with the decision made to cancel the National Remembrance Service in Christchurch," Goff said.
"It is with great regret that we are cancelling tomorrow's memorial event in Auckland. This is not a decision that we have made lightly but it is the right thing to do in light of decision taken in Christchurch.
"I have spoken with Muslim community leaders in Auckland and they have expressed their view to me that public health and safety is the most important consideration. Tomorrow we will hold in our hearts those who perished a year ago in the terrorist attack in Christchurch. The best way we can honour their memory is to continue to build a multicultural community that celebrates its diversity."
New Zealand Muslim Association President Ikhlaq Kashkari said the community fully supported the decision to cancel.
"The health of our whole community has to be the priority right now so we completely understand and respect the decision not to proceed with the event. We called this event Stronger Together and we will continue to work with all of our diverse community to ensure we can continue to build a more cohesive community here in Auckland and elsewhere in New Zealand."
- Additional reporting, NZME
