Heiko Maas held talks with Foreign Minister Mohammad Javad Zarif after earlier stops in the United Arab Emirates and Jordan on Sunday as part of his Mideast trip.
However, they have defended the nuclear accord saying that at least it puts curbs on Iran's nuclear programme and can be the basis for future talks.
Japanese Prime Minister Shinzo Abe spoke with US President Donald Trump over the phone on Tuesday (June 11) to discuss Iran, one day before the premier's three-day trip to the Islamic Republic amid mounting tensions between Washington and Tehran.
The U.S. pulled out of the deal over a year ago, and recently has imposed heavy new sanctions on Iran.
According to Maas, Germany and its European partners "have made the greatest effort to meet (their) commitments".
Following his opening remarks at a week-long meeting of the IAEA's Board of Governors which TV7 reported on yesterday, Amano noted that although Iran was now producing more enriched uranium than before, it remains unclear when it might reach stockpile limits that were set under the Joint Comprehensive Plan of Action - which is the technical term of the nuclear pact.
Meanwhile, the head of the United Nations atomic watchdog said Monday that Iran had already increased its uranium enrichment activities.
He would not elaborate on what kind of talks were necessary, saying that was a "political matter", and would not comment on whether he thought the USA should return to the JCPOA itself.
Maas conceded that due to the USA exit from the JCPOA, Iran's anticipated economic returns from the deal "never materialized".
Iran said on Sunday that Europe was not in a position to criticise Tehran for its military capabilities, and called on European leaders to normalise economic ties with the Islamic Republic despite USA sanctions or face consequences.
Then, on 20 May, the Atomic Energy Organization of Iran announced that it would quadruple its production of low-enriched uranium and had informed the IAEA, which is tasked with monitoring Iranian compliance with the nuclear deal.
Washington's European allies opposed its decision past year to abandon the nuclear deal.
The new sanctions come as Washington keeps up pressure against Iran over its ballistic missile program and for waging proxy wars in other Middle Eastern countries.
Maas stressed that the agreement was for the security of Europe is important. "An escalation of tension is becoming uncontrollable and military action wouldn't be in line with the interests of any party".
On Monday, Amano urged the countries involved in the Iran deal negotiations to continue dialogue with Iran in order to save the nuclear deal and prevent the country from developing nuclear weapons capabilities.
"We want to avoid any misunderstandings that would lead to automatic reactions that could lead to violence, " Maas said.
On the other hand, Maas talked about the escalation of tensions in the Middle East saying, "We and the European Union are seeking to reduce tensions in the region and will spare no effort in this respect".
Tehran has rejected the USA allegation.