German Chancellor Friedrich Merz said on Wednesday his relationship with U.S. President Donald Trump remained good despite a row between the two men over the Iran war, but he reiterated his worries over the economic impact of the conflict.

The spat reflects diverging views between the Trump administration and its European NATO allies on Iran and other issues, including the Ukraine conflict.

"From my perspective, my personal relationship with the U.S. President remains good. I simply had doubts from the start about what was begun with the war in Iran. That is why I have made that clear," Merz told reporters.

"In Germany and Europe we are suffering from the consequences, such as the closure of the Strait of Hormuz. This has a direct impact on our energy supply and a huge impact on our economic performance," said Merz, adding that Washington and Berlin were speaking to each other.

On Tuesday, Trump criticised Merz over his stance, saying in a social media post that the German chancellor thought it was "OK" for Iran to have a nuclear weapon and that he didn't know what he was talking about.

Merz has said Iran must not have a nuclear weapon.

Trump's comments followed a rebuke to Washington from Merz on Monday, when he said Iran's leadership was "humiliating" the United States by getting U.S. officials to travel to Pakistan for peace talks and then leaving them without results.

Merz also said he did not see what exit strategy the U.S. was pursuing.

Trump has harshly criticized NATO allies for not sending their navies to help open the Strait of Hormuz, which has remained virtually shut since early March, causing market turmoil and unprecedented disruption in energy supplies.

Despite a ceasefire in the U.S.-Israeli war with Iran, the conflict is deadlocked as both sides seek a formal end to the fighting.

-Reporting by Madeline Chambers; editing by Matthias Williams and Gareth Jones/Reuters