Voting against the recommendation were Dr Casey, Mike Lee, John Watson and Wayne Walker, who called for a total ban.
The vote came after an intense and concentrated lobbying effort by Greenpeace supporters, who inundated the councillors with more than 200,000 emails in just the past few days and turned out in protest today.
Spokesperson Steve Abel said while it was disappointing the council had opposed oil exploration, he had been happy to see a "really phenomenal swing" by councillors on the issue in the last few years.
The proposed block at the centre of the controversy stretches 61,485sq km across the offshore Taranaki Basin but cuts 125ha inside the North Island West Coast Marine Mammal Sanctuary, considered home to the critically-endangered Maui's dolphin.
The council recommendation asked that the block's shoreward boundary be amended to be at least 12 nautical miles offshore so it avoided the sanctuary and dolphin habitat, and that any activities have minimal impact.
Council chief planner Roger Blakeley said similar concerns thrown up by the previous block offer drew nearly the same response.
"It's a highly endangered species and our council had a very strong view that the exploration should not be occurring within that Maui's dolphin sanctuary area and being a further danger."
The recommendation further called on the Government to recognise the "sensitivity of potentially impacted areas"and ensure all risks of oil spill were minimised.
The Waitakere Ranges Local Board has also come out staunchly against exploration plans, submitting that a spill off Auckland's west coast would affect a "highly sensitive ecological area" that was a key breeding ground for several seabird species, among them the critically-endangered fairy tern.
Yesterday, marine scientists voiced their worries about any activity in or near the mammal sanctuary.
Auckland University marine biologist Dr Rochelle Constantine described the block proposal as "extremely unfortunate", with any activity within the sanctuary defeating its purpose of protection for the Maui's dolphin.
Department of Conservation officials had advised the Government of the block's overlap, although a DoC spokesman said the sanctuary already included regulations to lessen the impact of seismic survey activity.
Energy and Resources Minister Simon Bridges said the sanctuary was not designated as a Schedule 4 area, so was therefore not an exception.
Government research had shown the threat to Maui's dolphins from oil and gas development was "extremely small", he said.
"It's important to remember that block offer consultation is the first step in a very long process and only an extremely small percentage of permits lead to a discovery and then progress to mining permits and active mining."
