Last night, Mr Goff said he was asked by the Stop Stealing Our Harbour protest group to join the campaign, which was consistent with his opposition against extension of the wharf and further reclamation.
Mr Goff said the extensions should not proceed until a port future study was done.
"Otherwise you are forever condemned to making ad hoc changes and little by little the recreational value of the harbour is diminished by further extensions. This is an erosion of our harbour for a reason that hasn't been adequately justified."
The MP for Mt Roskill said he was speaking as Labour's spokesman on Auckland issues and any decision on standing for the mayoralty was some time off, probably early next year.
He said he had spoken with Labour leader Andrew Little about the mayoralty and had the support of party colleagues if he decided to stand.
Mr Goff is on a different side of the port issue from Mayor Len Brown, who is also a member of the Labour Party.
Mr Brown has argued the council was powerless to stop the wharf extensions and on April 30 used his casting vote to reach a compromise.
The compromise followed a port company offer to stop extending the western end of Bledisloe Wharf by 92m into the harbour, pending the completion of the port future study next year. Work on the eastern extension has already begun.