They moved there after thousands of people crossed the harbour bridge on foot yesterday, in a march organised by the Freedoms and Rights Coalition
Camping is not permitted in the Domain, which lies between the suburbs of Parnell and Grafton.
Auckland Council director of customer and community services Claudia Wyss said it was working with event organisers on a safety-first approach.
She said there was no timeline for reopening at this stage and the council apologises for any inconvenience.
The campers include people who took part in the march over the Harbour Bridge on Saturday yesterday to protest Covid-19 vaccine mandates, shutting down southbound traffic for an hour and a half.
The march was organised by Destiny Church's Freedoms and Rights Coalition. Leaders had been in talks with the Auckland Council and police about their presence late on Saturday, and promised to leave the site by 9pm that night.
A protester in a video has claimed to have mana whenua status, and said they were occupying a pa site at the domain.
Auckland Council said it was continuing to work with police and to engage constructively with the group.
However, it has raised concerns the marchers and protesters risked spreading Covid-19 by gathering.
In New Plymouth, about seven tents and about 30 people were at an anti-mandate protest beside the Coastal Walkway on Sunday morning.