Snells Beach ratepayers' association secretary Lesley Leversha said the community, without exception, rose as one at the thought of the library being taken away.
One resident, Laurie Webb, said the mayor's pledge would be welcomed by the community, but the closure should never have been suggested in the first place.
"I can't imagine any local body politician wanting to close libraries, which are at a centrepoint for the community," he said.
A former library assistant, Alexis McCullough, said Grey Lynn was one of the most vibrant, friendly and nuturing libraries she had worked in.
"If you take away a library from a community, you take away its heart."
Public Service Association assistant secretary Warwick Jones said there did not appear to be a clear rationale for closures, and the two libraries were an integral part of their communities.
Waitemata Local Board chairman Shale Chambers said the Grey Lynn library was a treasure and the board would not allow its demise.