Speaking at an event in Berlin entitled "The Future of Nuclear Order" on Wednesday, Maas said Washington's decision posed "major challenges to multilateralism and the nuclear non-proliferation architecture overall.
Germany's foreign minister said the basis of international order was trust and that "today's promise" should not be revoked via twitter tomorrow, in a reference to U.S. President Donald Trump.
He also warned Washington against favouring North Korea with an easing of sanctions unless Pyongyang showed verifiable steps within the nuclear order.
In a bid to save the Iran nuclear accord, Germany, France, Britain, Russia and China will meet in Vienna this week.
Germany along with its European partners have remained party to the Iran nuclear deal, which lifted sanctions on Tehran in exchange for curbing its atomic program, after U.S. President Donald Trump withdrew from it in May.
European countries also have been scrambling to ensure that Iran gets enough economic benefits to persuade it to stay in the deal.
US President Donald Trump announced on May 8 that Washington was walking away from the nuclear agreement, which was reached between Iran and the five permanent members of the UN Security Council - the US, Britain, France, Russia and China - plus Germany.
Iranian President Hassan Rouhani said on Tuesday that Donald Trump’s withdrawal from the Iran nuclear deal was “America’s worst and last option” as the move came with the highest prices for the US.
Stating that "Lift of sanctions were approved based on UNSC Resolution 2231," the President added: "US failed and is after making its unilateral sanctions against Iran a cross-border issue".
