"It has been clear at all times that this war is not a matter for NATO," Merz said, adding that the US and Israel "did not consult us prior to this war".

"There was never a joint decision on whether to intervene. That is why the question of how Germany might contribute militarily does not arise. We will not do so," Merz said at a press conference alongside his Dutch counterpart Rob Jetten.

US President Donald Trump on Sunday called for nations including South Korea, France, China and Britain to help ensure safe passage in the Strait of Hormuz, which Iran has declared closed to US and US-allied traffic.

He later upped the pressure on NATO allies, telling the Financial Times newspaper that the alliance faced a "very bad" future if its members did not do their bit to reopen the strait.

Merz ruled out Germany sending ships to the Strait of Hormuz.

"For as long as the war continues, we will not be involved in ensuring free passage in the Strait of Hormuz by military means," he said.

Merz's spokesman Stefan Kornelius earlier also said the war had "nothing to do with NATO".

"NATO is an alliance for the defence of territory" and "the mandate to deploy NATO is lacking", Kornelius told a regular press briefing.

At a separate briefing on Monday, Defence Minister Boris Pistorius said Germany wanted all those involved to prevent "further military escalation".

"There will be no military participation" from Germany but Berlin is prepared to support diplomatic efforts to "to ensure safe passage through the Strait of Hormuz", he said.

"We have a situation which we did not provoke... This war started without any consultations," Pistorius added.

Germany's main responsibility is "for the eastern flank and the high north", he said, and "we stay committed to that but we can't be anywhere in the world".

"What does Donald Trump expect from a handful of European frigates in the Strait of Hormuz that the mighty US navy cannot manage alone? This is the question I find myself asking," Pistorius said.