An Israeli air strike on the southern suburbs of Lebanon's capital Beirut has put further pressure on attempts for a US-Iran deal to end the war, although Donald Trump says a truce remains close.
The attack on Dahieh, where the Iran-backed armed group Hezbollah is based, came after the US said a deal with Iran would be signed on Sunday.
Israel said the attack was in response to Hezbollah firing towards northern Israel. The strike opens the possibility of further hostilities, as Iran vowed to respond by attacking Israel.
Trump said the attack "should not have happened particularly on a special day when we are so close to a Peace Deal with Iran".
"This could be the beginning of a long and beautiful peace - Let's not blow it!" the US president added.
At least three people were killed and 15 others injured in the strike, Lebanon's state media said.
Iran has insisted that any truce should also include the end of the war in Lebanon, where Israel has been fighting the militia and political party Hezbollah. Israeli officials, however, reject this, saying the military operations must continue.
Since the start of this round of conflict in March after Hezbollah launched rockets into Israel, the Israeli military has carried out extensive air strikes across Lebanon and an invasion of the south of the country.
Israeli officials say the goal is to protect communities from Hezbollah's rockets and drones.
In Israel, where there is public support for the war to continue, a consensus seems to have emerged that the potential US-Iran deal could represent a setback for the country, as its military successes against Iran and Hezbollah do not appear to have been translated into what could be seen as a strategic victory.
Based on leaks of the deal, an Israeli military official described it as "very bad" and "catastrophic" to the country's Ma'ariv newspaper.
An Israeli defence official told N12 TV channel that "none of the goals set by Israel have received an immediate response in the agreement".
The Lebanese government has also tried to disassociate the situation in the country from Iran, to reduce Tehran's influence domestically and weaken Hezbollah, as part of efforts to disarm the group.
The Israeli military said the attack on Dahieh targeted what it described as a command centre used by Hezbollah after the group launched "aerial targets toward Israel".
In his social media post, President Trump said: "Israel has the right to defend itself against threats, but the attack it was responding to was very small and meaningless, nobody was hurt, injured, or killed, and should not disrupt this important process".
He also said "there should be no more attacks by Israel anywhere in Lebanon, but there should also be no more attacks by any other party, including Hezbollah, against Israel".
Mohammad Bagher Ghalibaf, Iran's chief negotiator in the ongoing talks with the US, said Israel's attacks showed the US was not fulfilling its commitments.
Iran's senior military official Brig Gen Mohammad Jafar Assadi also warned that the attack would not go "unanswered".
Trump has typically been an ardent proponent of Israel during both of his terms in the White House, but his attempts to extricate himself from a potentially drawn-out and increasingly costly conflict in the Middle East have been frustrated by Israel's ongoing operation in Lebanon.
Israel and the US began launching strikes across Iran on 28 February, prompting Iran to attack Israel and US-allied states in the Gulf - as well as effectively closing the Strait of Hormuz, a key shipping route for the world's oil and liquefied natural gas.
Lebanon was drawn into the war between Israel, the US and Iran on 2 March, when Hezbollah launched rockets into Israel in retaliation for an Israeli strike that killed Iran's supreme leader. Israel responded by launching a bombing campaign across Lebanon and invading a significant part of the country's south.
Despite having agreed a ceasefire in April, the US and Iran have exchanged intermittent fire.
For decades, Iran has been accused by Western countries of trying to build a nuclear weapon. It has denied the accusations saying its programme is for peaceful purposes - to generate electricity and for research purposes.
