The signatories to the landmark accord met for the first time since Donald Trump, the United States president, withdrew in May to discuss how they could salvage the deal in the face of a reimposition of U.S. sanctions.
Earlier in the day, Zarif said he was in Vienna "to listen to practical solutions, rather than slogans".
During a visit to Europe this week President Hassan Rouhani warned that Iran could reduce its co-operation with the United Nations nuclear watchdog, having already threatened Trump of the "consequences" of fresh sanctions against Iranian oil sales. "It only included some general promises like previous European Union statements", Tasnim quoted Rohani as saying.
"The responsibility for the change of Iran's cooperation level with... falls on those who have created this new situation", he said, according to the Reuters news agency.
In another phone conversation with French President Emmanuel Macron late on Thursday, Rouhani described Paris' efforts to save the nuclear deal as "positive" but noted that "Europe's proposed package for keeping up cooperation in the JCPOA does not meet all our expectations".
Besides, Commander of the IRGC Quds Force Qasem Soleimani on Tuesday lauded Rouhani for responding strongly to a USA plan aimed at blocking Iran's oil sales, saying "this is the Dr. Rouhani we used to know and the one he should be".
He said the European powers but also Russian Federation and China were working on coming up with a financial mechanism to mitigate planned tough US sanctions. "We are trying to do it (economic package) before sanctions are imposed at the start of August and then the next set of sanctions in November".
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Maas called the European offer "attractive" but conceded that "we won't be able to compensate for all the effects of enterprises withdrawing from Iran because they see their American business interests threatened by the sanctions".
Iran's remaining partners in the 2015 nuclear deal vowed Friday to keep the energy exporter plugged into the global economy despite the USA withdrawal and sanctions threat.
While the other signatories have vowed to stay in the accord, dozens of European, Russian, and Asian companies have announced plans to pull out of Iran for fear of incurring US penalties when sanctions are reimposed in November.
Iranians have complained that the hoped-for rise in foreign investment and trade after the deal has not materialised.
Iranian officials have said that key for them is to ensure measures that guarantee oil exports do not halt, and that Tehran still has access to the SWIFT global bank payments messaging system or an alternative.
In a joint statement, the foreign ministers said they are still committed to the economic relations with Iran including "Iran's continued oil and gas exports" and other energy products.
This week, the European Parliament approved a key component of the package, giving the European Investment Bank authority to invest in Iran despite the US sanctions. "Enough with the policy of appeasement and weakness regarding Iran".