The protest, organised by Oil Free Otago, was held outside National MP Michael Woodhouse's Dunedin office, because he was ''the Government's representative in Dunedin'', Oil Free Otago spokeswoman Rosemary Penwarden said.
In a statement responding to the protest, Mr Woodhouse said: ''We live in a free democracy where people are entitled to publicly share any concerns they have.''
The Dunedin protest comes after a crowd of several thousand marched in Auckland at the weekend.
They were protesting against the New Zealand Petroleum Summit being held in Auckland this week, and yesterday's announcement.
Ms Penwarden said Oil Free Otago wanted the Government to withdraw the block offer.
''It comes down to insanity that we're spending more time exploring for fossil fuels that we must not burn'' if the goal is to keep global warming under 2degC, she said.
Associate zoology professor Liz Slooten said she was concerned about prospecting with seismic blasts - which can be dangerous for marine mammals - but that it was ''difficult to tell what the impact would be''.
''It's hard to know what animals are out there, because there's very little data on what marine mammals are out there,'' she said.
In order to have firm data on marine mammal numbers, there would have to be a marine mammal survey, which was not obligatory under New Zealand law, Prof Slooten said.
