The event, scheduled on Sunday afternoon, was expected to be attended by thousands of people travelling from around New Zealand and from overseas.
Prime Minister Jacinda Ardern said while there was no "community transmission" of COVID-19 at this stage in New Zealand, 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," said Ardern.
Meanwhile, the sixth case of COVID-19 was confirmed by the chief executive of Waitematā District Health Board Dr. Dale Bramley in Auckland on Saturday.
The person is an Auckland man in his 60s who recently travelled to the United States.
The man, who first started feeling unwell at the beginning of the week, has improved considerably and now reports feeling almost completely recovered. He will be at home in self-isolation and will be monitored daily by health services, according to the Ministry of Health.