Russia and Germany on Thursday urged countries in the Middle East to show restraint and Israel said it was preparing to “meet all its security needs” in a region on edge over an Iranian threat to strike Israel.

The German airline Lufthansa, one of only two Western carriers flying to Tehran, extended a suspension of its flights to the Iranian capital and Russia warned against travel to the Middle East.

Iran has vowed revenge for the April 1 airstrike on its embassy compound in Damascus that killed a top Iranian general and six other Iranian military officers, ratcheting up tension in a region already strained by the Gaza fighting.

Prime Minister Benjamin Netanyahu said Israel was keeping up its military operation in Gaza but making security preparations elsewhere.

“Whoever harms us, we will harm them. We are prepared to meet all of the security needs of the State of Israel, both defensively and offensively,” he said in comments released following a visit to an air force base.

Conflict has spread across the Middle East since the eruption of the fighting in Gaza, with Iran-backed groups declaring support for the Palestinians waging attacks from Lebanon, Yemen and Iraq. Tehran has avoided direct confrontation with Israel or the United States while declaring support for its allies.

German Foreign Minister Annalena Baerbock called her Iranian counterpart Hossein Amirabdollahian to urge “maximum restraint” to avoid further escalation.

Russia’s foreign ministry told citizens they should not travel to the Middle East, especially to Israel, Lebanon and the Palestinian territories.

“Right now it’s very important for everyone to maintain restraint so as not to lead to a complete destabilisation of the situation in the region, which doesn’t exactly shine with stability and predictability,” Kremlin spokesperson Dmitry Peskov told a news briefing.

Israel has not claimed responsibility for the April 1 attack, for which Iranian Supreme Leader Ayatollah Ali Khamenei said on Wednesday that Israel “must be punished and it shall be”, adding that it was tantamount to an attack on Iranian soil.

Biden says Iran threatens ‘significant attack in Israel’

US President Joe Biden said a day ago that Iran was threatening to launch a “significant attack in Israel”, and that he had told Netanyahu that “our commitment to Israel security against these threats from Iran and its proxies is iron-clad.”

Iran is the third-largest oil producer in the Opec group and oil prices rose after jumping a dollar a barrel in the previous session.

Late on Wednesday, an Iranian news agency published an Arabic report on the X platform saying the air space over Tehran had been closed for military drills, but then removed the report and denied it had issued such news.

Lufthansa said it would probably not fly to Tehran before April 13. Austrian Airlines said it was still planning to fly on Thursday but was adjusting timings to avoid crew having to disembark for an overnight layover.

Iranian air space is also a key overflight route for Emirates’ and Qatar Airways’ flights to Europe and North America.

Emirates, Qatar Airways, Turkish Airlines, Aeroflot and Air Arabia, among the airlines that fly to Tehran, did not immediately respond to requests for comment.