Tehran's top diplomat Mohammad Javad Zarif praised them for their "will to resist" US pressure, two months after President Donald Trump walked away from the landmark accord.
Britain, France and Germany along with Russia and China met with Iran in Vienna to offer economic benefits and assurances that would lessen the blow of sweeping US sanctions announced by Trump.
They said they remained commited to the accord and to building up trade and investment links with Iran, including "the continuation of Iran's export of oil and gas" and other energy products.
"All the members, even the three allies, have committed and have the political will to take action and resist the United States," Iran's Foreign Minister Zarif told a Vienna news conference broadcast by the Fars news agency.
"This is the first time they have shown this level of commitment, but we will have to see in the future what they really want to do and what they can do," Zarif said.
"If they continue to demonstrate the political will they showed today, they will get things done without any problem."
Iranian President Hassan Rouhani had Tuesday labelled the US push to cut Iran's oil production to zero "a baseless fantasy" and an attempt to drive "imperialist policy in flagrant violation of international law".
Read more at https://www.channelnewsasia.com/news/business/world-powers-back-iran-oil-exports-despite-us-sanctions-threat-10507038