BERLIN - German Chancellor and Christian Democratic Union (CDU) leader Angela Merkel has condemned the decision of US president Donald Trump to withdraw from the Iran nuclear accord on Friday.

Speaking at the annual Catholic church convention in Muenster, Merkel said that Washington's move was a "reason to be concerned, as well as a reason to feel regretful." She criticized that it was "not right" to unilaterally terminate such an important international agreement.

In an earlier phone conversation with Iranian president Hassan Rouhani, the chancellor joined state representatives from France and the United Kingdom in emphasizing that her country remained committed to the terms of the nuclear accord.

The landmark deal to end Iran's nuclear weapons program in exchange for a lifting of economic sanctions was signed in 2015.

According to Merkel's official spokesperson Steffen Seibert, the German chancellor proposed new talks addressing Iran's ballistic missile program as a potential means to salvage the deal. Additionally, she urged Tehran to help de-escalate spiralling conflicts in the Middle East.

Merkel stressed Friday that the fate of the Iran nuclear deal was a "matter of war and peace", highlighting reports of new hostilities between Iranian and Israeli troops on the Syrian-Israeli border.

Meanwhile, Washington, together with the United Arab Emirates (UAE), has already re-activated the first economic sanctions against Iran.

German minister for the economy Peter Altmaier warned on Friday that his government had "no judicial means to protect or exclude" German companies from the financial effects of US sanctions.

By contrast, his French counterpart Bruno Le Maire expressed confidence that French trade with Iran will continue unperturbed and urged the international community not to accept Washington's claim to the role of the "economic policeman of the world."

French, British and German representatives are scheduled to hold related emergency talks with their Iranian counterparts on Monday.