"The science is clear, to prevent catastrophic climate change we cannot burn all the fossil fuels which we've already found, let alone explore for more," Barber said.
"The world is already struggling to adapt to a changing climate. The Government needs to stop handing out exploration permits, stop all existing exploration and drilling, and provide for a just transition for workers in the industry."
Barber said a "just" transition meant the Government would provide support for anyone who would be affected by the end of the oil and gas industry, so it would not "destroy these communities".
"The solutions to climate change must include and benefit the people most affected by it - indigenous peoples, people of colour and those struggling on low incomes. Those most affected by climate change are the least responsible for it."
Barber said the activists wanted to see change not only for the environment, but for people living in poverty and dealing with the effects of colonisation.
"We want to see a world where these problems are solved holistically."
Barber said organisers of the protest were preparing to provide support for anyone arrested or "treated roughly" by police at the rally, but hoped it would not be necessary.
The blockade would be "completely non violent".
Other groups joining the protest include Climate Justice Taranaki, Te Ara Whatu, Pacific Panthers, 350 Aotearoa, Pacific Climate Warriors, Auckland Peace Action, Peace Action Wellington, People Against Prisons Aotearoa, Unions Wellington, Oil Free Otago, Catholic Workers, Indigenous Peoples Uprising and Te Ikaroa.
"We're shocked that the summit is being held in a council-owned venue, particularly since Mayor Justin Lester has previously committed to ethical guidelines for events taking place in council venues," Barber said.
The rally calls for the Government to not commit to any new permits and to stop all drilling and prospecting for oil and gas as part of a just transition for workers and communities.
It also calls for the oil and gas industry to stop drilling and prospecting and "clean up the damage you have caused and make amends to the communities you've harmed".
Petroleum Exploration and Production Association of New Zealand, which holds the conference, has been contacted for comment.