Iran's main concern is that renewed USA sanctions will have a far-reaching impact on the willingness of non-American companies and banks to deal with Iran, crippling its trade, oil exports and an already strained economy.
"The talks with the Europeans, Iran and the other signatories to the agreement are therefore also about how it can be possible to continue trade with Iran", Maas said.
European firms, especially those from France and Germany, rushed to invest in Iran following the 2015 accord, under which Tehran agreed to freeze its nuclear program in return for the repeal of punishing global sanctions.
He made the remarks in an interview with Fox News, after U.S. President Donald Trump withdrew from the deal on Tuesday. He also said Iran should receive economic benefits promised in the accord, even if the United States reinstates sanctions.
They include retaliatory sanctions, allowing the European Investment Bank to invest directly in Iran and co-ordinating euro-denominated credit lines from European governments.
"This agreement remains important for our shared security", a joint statement signed by French President Emmanuel Macron, German Chancellor Angela Merkel and UK Prime Minister Theresa May said on Tuesday. If the United States punishes European companies for doing business with Iran, foreign companies will likely walk away from Iran.
But he added: "If the nuclear deal is to continue, the interests of the people of Iran must be assured".
"The consequences of American sanctions go well beyond goods shipped by American companies, " Bolton said.
"I would like to point out that Russian Federation and other participants in the deal - China and the European countries - also have their legitimate interests enshrined in this agreement", he added.
European Union leaders aim to show a united front on preserving the Iran deal when they meet for a pre-summit dinner in Sofia on Wednesday, officials said.
Top Iranian officials, including Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei and President Hassan Rouhani, have said Europeans must give the required guarantees in order for Tehran to stay in the deal.
While announcing his decision, Trump called the agreement "defective at its core", claiming that after the lifting of the sanctions Tehran "used its new funds to build nuclear-capable missiles, support terrorism and cause havoc throughout the Middle East and beyond".
But European diplomats were despondent.