Representatives from conservation groups told local media that the areas surrounding the port are too important to be developed.
They added that port development sites need to be independently assessed for environmental impacts and that the community should have more influence in the planning.
Government officials have told local media that development of the port would be subject to an environmental effects statement, which would follow about two years of detailed scientific studies.
September 1 saw the integrated management of the ports of Hastings and Melbourne, which will have the Port of Melbourne Corporation overseeing the expansion of the two ports.
The conservation groups have united to draft a joint statement calling for the halt to development plans.