"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, its support for terrorism and proxies.

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

But Merz said a total collapse of the Iranian state would spread 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."

"We want this state to be able to function on its own," he added of Iran.

"And that is why 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."

"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 crisis in the Middle East a major humanitarian emergency, and insisted all fleeing civilians should be granted safe passage.

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