"I expressed my concerns to him regarding the announced attacks on the power plants in Iran," Merz told a Berlin press conference about their Sunday phone call.

"I am grateful that he said today he is postponing them for another five days."

The US president abruptly said in a post on his Truth Social platform that he was ordering a halt to strikes on Iran's energy infrastructure, claiming the United States had held "very good" talks with Tehran.

Iranian media has denied that any negotiations took place.

Merz, however, welcomed that Trump "is now opening the possibility for immediate and direct contact with the Iranian leadership".

The chancellor said he had offered Trump Berlin's diplomatic assistance to mediate the conflict, which has seen global energy prices rise sharply and triggered concerns of a severe economic fallout.

"We have good contacts throughout the region," Merz said.

"We are not yet at the point where we are discussing joint measures, but I offered to work together and do everything we can to achieve a ceasefire in the region as quickly as possible."

Merz has repeatedly condemned Iran's leadership and voiced initial support for the US-Israeli war, but has since expressed growing concern about the costs of the conflict.

Germany, along with other European NATO members, has also repeatedly stressed that they would not become directly involved in the conflict.

That has prompted Trump, who has variously demanded NATO help in opening the Strait of Hormuz to ship traffic, to slam those allies as "cowards".