Iran on Monday said it was ending its latest military operation against Israel after the first exchanges of fire between the foes since a shaky ceasefire began, but warned it could inflict a more "crushing" response.
Iran fired dozens of missiles at Israel overnight and Israel responded by targeting military sites in the Islamic republic, sparking fears the escalation could usher in a new full-scale conflict after the April 8 truce.
"Israel and Iran must immediately stop 'shooting.' President DONALD J. TRUMP," the US leader wrote on his Truth Social network.
Minutes later, he added in a new post that "final negotiations" towards peace were proceeding "subject to ignorance or stupidity getting in its way."
Iran's military command then said it was halting the operation against Israel after delivering a "painful response".
But it warned "that should acts of aggression and hostility continue, including in southern Lebanon, much more severe and crushing measures than before will follow".
Shortly after, Israel's army intercepted three projectiles fired from Lebanon, according to an AFP journalist near their shared border, with the military confirming the munitions had targeted its forces operating in Lebanon's south.
"Some of the projectiles were intercepted prior to crossing into Israeli territory, and an additional projectile fell near -army- soldiers. No injuries were reported," the military said.
Tehran's earlier strikes followed attacks by Israel against targets of the Iran-backed Lebanese group Hezbollah in the southern suburbs of Beirut.
Iran had repeatedly warned it would strike Israel if the Lebanese capital was targeted.
No casualties have been reported in either Israel or Iran after the exchange of fire.
The Israeli military said it struck and dismantled Iranian defense systems deployed across several areas in the country. Iran fired nearly 30 missiles towards Israel since Sunday night, an Israeli military official said.
An AFP correspondent also saw a missile fall in agricultural land in the area of Najha, in the countryside of the Syrian capital Damascus, causing a fire around the impact site but no reported human casualties.
"Material damage is minor, but the psychological impact is significant. The area is home to children, farm caretakers, livestock and solar power installations," said Fadil Ataya, a local farmer.
A military source told the Tasnim news agency that "Iran is prepared for a long-term war with the Zionist regime and for strikes against US interests" in the region.
It also remains unclear who is leading decision-making in Tehran with Mojtaba Khamenei, said to have been wounded in a US-Israeli strike, yet to appear in public after taking over from his father Ali Khamenei who was killed on the first day of the war on February 28.
The European Union's top diplomat Kaja Kallas called on both sides to "sit down to a negotiation table and agree", adding that "the region does not need an escalation."