"What I noticed during this meeting is that all the members, even the three allies, have committed and have the political will to take action and resist the United States," Foreign Minister Mohammad Javad Zarif told a press conference, broadcast by Iran's Fars news agency, after talks in Vienna.

Three European nations along with Russia and China vowed at the meeting to keep the energy exporter plugged into the global economy despite the US withdrawal and threat of renewed sanctions, including on Iran's key crude oil exports.

The diplomats said they remained committed to the 2015 accord and to building up economic relations with Iran, including "the continuation of Iran's export of oil and gas" and other energy products.

"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."

The foreign ministers agreed on an 11-point list of joint goals in the Austrian capital, where the accord was signed three years ago with the aim of reining in Iran's atomic programme in return for sanctions relief that promised greater trade and investment.

Iran has suffered worsening financial turbulence since US President Donald Trump abandoned the accord in May.

Washington has warned other countries to end trade and investment in Iran and stop buying its oil by early November or face punitive measures.