The union's national president, Garry Parsloe, said the aim of the action was to get negotiations restarted.
"We should be back in mediation," Mr Parsloe said. "It's gone on too long."
The port, unable to get the union to agree to a changed rostering system, recently suggested that all workers could be made redundant and replaced with contractors.
Some workers were described as being panicked about the prospect of losing their jobs or being subjected to extreme shiftwork.
"They're dealing with the uncertainty, the not knowing. It's terrible," said stevedore Grant Williams.
Management want to break up the eight-hour shifts that lead to hours of downtime.
Mr Williams said the workers were willing to make changes, but the existing collective agreement - a document built up over decades of negotiations - needed to be the starting point.
It represented standing up for decent conditions, he said.
The waterfront felt like the last bastion for workers' rights.
Council of Trade Unions president Helen Kelly said the waterfront dispute was a flashpoint in a broader movement towards casualisation.
"The deal about work is you go to work and you earn a wage that pays your rent, buys food, buys power and allows you to sustain a decent life."
Ports of Auckland chief executive Tony Gibson disputed the union's claims that it had asked for further mediated negotiations.
"I'm not sure it's miscommunication. I think it's misleading," Mr Gibson said. "They haven't asked us or the Labour Department."
He said that after 90 hours of negotiations the union had yet to officially respond to the port's latest offer.