The US president lashed out at France on Tuesday, writing on social media that Paris had been "very unhelpful" during the war with Iran, which has since spread across the Middle East.

"I'm well aware that sometimes Europe can be seen as a continent that is slower than others," Macron told an audience of Japanese business leaders and investors in Tokyo.

"But predictability has value, and we have demonstrated that over all these past years and, dare I say, even these past weeks: we are where you know we will go," he added.

"That's not bad, in times like these, believe me."

Macron criticised countries that said they were "going much faster" than their allies, but "you don't know whether the day after tomorrow they will still be in that position, and whether tomorrow they won't make a decision that could hurt you without even informing you".

The remark was a reference to the month-long US-Israeli war on Iran, which has responded by virtually closing the vital Strait of Hormuz, through which a large share of the oil imported by Japan normally transits.

Before meeting Japanese Prime Minister Sanae Takaichi later Wednesday, Macron spoke of the "dramatic impacts on energy" as a result of the war.

"Europe stands by your side," he said.

"We are also on the side of international law, on the side of negotiation and the return of diplomacy."

Japan depends on the Middle East for 95 percent of its oil imports and has had to dip into strategic stockpiles to temper the impact of rising fuel prices since the start of the war.

During Macron's talks with Takaichi, "the crisis in the Middle East will be at the heart of discussions", the Elysee said ahead of his Asia trip, which will also include a visit to South Korea.

France and Japan are also expected to discuss security and partnerships in the space sector, and intend to sign a roadmap on nuclear power in Japan, the Elysee said.