The decision by Lebanon’s foreign ministry has heightened fears of internal instability. Hezbollah, the Iranian-backed militant group and political party, was quick to condemn the move.

The current restrictions on the internet in Iran are coinciding with Nowruz, the observance of the Persian New Year.

The weeklong fight over Iran’s next leader pitted the Revolutionary Guards against moderates. The generals won, but only over spirited resistance.

Some residents described the strikes overnight Monday into Tuesday as among the worst they had experienced since the war started.

Many in Iran feel helpless in the face of their entrenched system, and some are becoming increasingly embittered by the fierce American and Israeli bombardment.

Ali Larijani, the head of Iran’s Supreme National Security Council and a close confidant of Ayatollah Ali Khamenei, said Iran was determined to avenge the killing of the leader.

Israel said one of its F-35 fighter jets, known as an Adir, had downed another crewed plane over Tehran, the Iranian capital. Iran did not immediately comment.