Senior diplomats from Iran and five world powers began meetings in Vienna on May 25 to try to prevent a 2015 nuclear deal from collapsing after Washington's withdrawal from the deal earlier this month.
"It won't be easy, but we'll try," Iranian Deputy Foreign Minister Abbas Araqchi said ahead of the talks.
U.S. President Donald Trump pulled out of the agreement on May 8 and announced it would reinstate sanctions against Iran.
Iranian leaders have said they will uphold their side of the deal, which involves strict curbs on their nuclear program, if Britain, France, Germany, Russia, and China uphold theirs by making sure that Iran can keep doing business with the world, despite the revived U.S. sanctions.
"To be honest with you, we are not confident," said another senior Iranian official, adding that Tehran wants European powers to present it with a package of measures “by the end of May."
Iranian ministers are under orders from Supreme Leader Ayatollah Ali Khamenei to seek guarantees from the Europeans for Iranian oil sales and trade, as well as their agreement to spurn U.S. efforts to negotiate a stronger and broader deal with Tehran.
Khamenei laid out a series of conditions on May 23 that he said must be met for Iran to stay in the deal.
The European powers are expected to highlight EU efforts to legally shield European companies that have established ties with Iran from the U.S. sanctions so they can continue doing business in Iran.
Diplomats said the European Union was trying to make sure that such businesses are not affected in particular by U.S. sanctions prohibiting Iran from using the U.S. dollar or U.S. financial institutions to transact business.
Iranian officials were expected to carefully scrutinize the package of measures EU officials have cobbled together to try to counter the U.S. sanctions.
Some European officials have been openly skeptical that the measures will be effective in keeping businesses from fleeing Iran. Several major corporations, including France's Total and Germany's Allianz, have already announced they are leaving unless they receive exemptions from the U.S. sanctions.
"I think this is a moment of truth for the Europeans," EU chief diplomat Federica Mogherini said this week.
The meeting of foreign ministers is the first since U.S. President Donald Trump on May 8 abandoned the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), which originally provided near-universal sanctions relief in exchange for curbs on Iran's nuclear activities.
In pulling out, Trump argued that the agreement would not stop Iran from eventually developing atomic warheads, and that it did nothing to check Iran's ballistic-missile program or its involvement in regional conflicts in Yemen and Syria.
European and Russian leaders say the deal has accomplished its goal of preventing Iran from developing nuclear weapons while contributing to stability in the Middle East.
With reporting by dpa and Reuters