"An endless war is not in our interest. The same applies to a collapse of Iranian statehood or proxy conflicts fought on Iranian soil," he said in a statement.

"Such scenarios could have far-reaching consequences for Europe, including for security, energy supply and migration."

He added that "we share the goals of the United States and Israel regarding the Iranian nuclear and missile programme, Tehran's threats against Israel, and its support for terrorism and proxies.

"The Iranian people have the right to freely decide their own destiny."

He warned against chaos, a point he also stressed speaking at a trade fair in Munich.

Germany and its European allies were "pushing hard for Iran's sovereignty to be preserved", he said there.

"We do not want to see a Syrian scenario here," he added.

"I am appealing both in Washington and in all talks with the Israeli government to create the conditions for this country to be stabilised as quickly as possible."

Merz said that "we naturally have a strong interest in this ourselves in order to avoid new waves of refugees from the region".

The United Nations refugee agency on Friday declared the Middle East war a major humanitarian emergency, and insisted all fleeing civilians should be granted safe passage.

UNHCR said the war -- which began on Saturday when Israel and the United States launched strikes on Iran and has spread across the region since -- had already caused large numbers of people to flee their homes.

German Foreign Minister Johann Wadephul said Berlin would provide 100 million euros ($116 million) in humanitarian aid for Lebanon, which became engulfed in the war after the Iran-backed group Hezbollah on Monday fired missiles at Israel to avenge the death of Iranian supreme leader Ali Khamenei.

"We are currently seeing a new dynamic and a dramatic situation in Lebanon with many internally displaced persons, and we want to help throughout the region in order to provide assistance on the ground," Wadephul said.