As one of a group of signatories to the so-called Iran Nuclear Deal, in which international sanctions against the country have been lifted in return for Tehran agreeing to forgo nuclear weapons, Germany has been unsettled by intimations by US President Donald Trump that the US might pull out of the arrangement. So it was no accident that German Foreign Minister Gabriel spent much of the press conference following talks with Zarif addressing the issue.

Gabriel said the deal had prevented an "unrestricted nuclear arms race" in the Gulf region and described his country's support for it as unwavering.

"We stand behind this agreement and want to support all the parties in their efforts to fulfill it," Gabriel said. "As the Federal Republic of Germany and as Europeans we would oppose any attempts to call it into question."

Gabriel added that according to the International Atomic Energy Agency, Iran has been meeting its obligations under the deal. Zarif thanked Germany for helping lift what he called the "unjust sanctions."

"From the very beginning, Germany played an important role in the negotiations," Zarif said. Aside from Germany, the nuclear deal included all the permanent members of the United Nations and the European Union.

In a statement German Economy Minister Brigitte Zypries echoed Zarif's calls for economic ties between the two countries to be further expanded. German exports to Iran in 2016 totalled around 2.6 billion euros ($2.9 billion).

Punished for the deeds of others?

The Iranian foreign minister also commented on the Supreme Court decision in the US that partially sanctioned Trump's entry ban on people from six Muslim-majority countries, including Iran, that the US president claims sponsor terrorism.

Using the colloquial name for Trump's executive order, Zarif said that the "Muslim ban" would encourage rather than deter terrorism and was aimed at the wrong groups.

"It's regrettable," Zarif said. "The citizens from the countries on the list have never participated in any acts of terrorism against the United States and yet they are punished for acts of terrorism by the citizens of other countries. The problem is that, for some, support for terrorism is measured by how much money they spend buying arms from the US and not by actual acts of terrorism."

Gabriel did not comment on the issue.

You can't choose your neighbors

Gabriel and Zafir said that they had also discussed the Middle East diplomatic crisis that has seen Saudi Arabia, Bahrain, Egypt and the United Arab Emirates break off relations and impose embargoes on Qatar.

Ahead of his visit to Berlin, Zafir had urged Europe to take a greater role, but Gabriel was somewhat non-committal, saying only that Germany, together with the US, supported efforts by the emir of Kuwait to get the two sides to the negotiating table.

Iran has supported Qatar in the conflict, but Zarif said that both sides in the conflict had no choice but to learn to live side by side.

"Neighbors are not a choice - they're a fact," said Zarif. "A fact of geography is a fact of geography."

Worlds apart

Critics of Iran accuse Zarif of being a slick diplomat who conceals the harsher policies of his government behind a media-friendly smile.

Gabriel acknowledged that on a range of issues, including Iran's consistent calls for the eradication of Israel, the two countries were "worlds apart."

"But that shouldn't lead us to question an area in which we've achieved success," Gabriel added. "We shouldn't misuse conflicts in other areas, many of which existed before the nuclear deal, to call the nuclear deal into question."

Outside the German Foreign Ministry anti-Iranian demonstrators erected mock gallows to protest against Tehran's human rights abuses and support for Syrian leader Bashar al-Assad in that country's bloody civil war. They chanted "Zarif must go" and held up signs calling for an end to state executions in Iran.