German Chancellor Olaf Scholz on Wednesday slammed Tehran's missile barrage fired at Israel the previous evening, while Berlin summoned the Iranian ambassador over the attack.

"The Iranian missile attacks on Israel must be condemned in the strongest possible terms," Scholz said, warning of "a further escalation of the already tense situation in the Middle East".

"Iran risks setting the entire region ablaze," he said in comments on social media platform X.

The foreign ministry stressed German citizens should leave Iran, warning them against any travel to the Islamic republic due to the "volatile and very tense" situation in the region.

The ministry also said it had summoned Iran's ambassador over the attack.

A charge d'affaires responded to the summons as the ambassador was not in Berlin, ministry spokesman Sebastian Fischer told reporters.

Fischer rejected Iran's claim that the attack was justified as a response to Israel's actions, including the killing last week of Hezbollah chief Hassan Nasrallah.

"We can only speak of self defence when one is repelling an ongoing or imminent threat, otherwise it is revenge," he said, adding that "revenge is not a category in international law".

Scholz meanwhile also said Berlin would continue its efforts to broker a truce between Israel and Iran-backed Lebanese group Hezbollah.

"Such a ceasefire must be the start of the full implementation of UN Security Council Resolution 1701, which clearly stipulates that Hezbollah must withdraw from the border area with Israel," he said.

The German leader reiterated a call for a Gaza ceasefire ahead of the anniversary of Hamas's October 7 attack on Israel, which sparked the war in the coastal Palestinian territory.

Palestinian militants took 251 hostages that day, with 97 still being held inside the Gaza Strip, including 33 who the Israeli military says are dead.

The hostages' "fate must be an incentive for everyone to reach an agreement based on the proposals made by US President (Joe) Biden", Scholz said.