Ports of Auckland says it is going ahead with proposed redundancies and will contract out its labour force.
Some 300 members of the Maritime Union working at the port had gone on a 48-hour strike from 11pm on Monday.
The union rejected Port of Auckland's latest offer in the long-running dispute over a collective contract, and now the company says it has rejected a counter-offer from the union.
Ports of Auckland says it is progressing with plans for redundancies due to the loss of business after Danish shipping giant Maersk and dairy cooperative Fonterra decided to use other New Zealand ports, including Tauranga and Napier.
Ports of Auckland says it will begin consultation this week over contracting out the labour force, but expects most of the affected employees will continue working for the company under other contractors.
Chief executive Tony Gibson says the company has run out of time trying to bargain as more customers and more jobs will be lost in coming weeks.
Both parties are due to enter mediation talks on Thursday.
Mr Gibson says staff will be briefed at a series of meetings this week.
Auckland mayor Len Brown supports both parties, but says the dispute has gone on long enough.
Mr Brown says he believes the negotiations are reaching a critical phase and hopes an deal will be reached in the next few days.
Ports of Auckland is owned by Auckland Council Investments Ltd, a council-controlled investment company.