Soon after the Israeli warning on Sunday, several blasts were heard and a large fire was seen in Beirut's southern suburbs. There was no immediate information on what caused the explosions, or details of any casualties.
Panicked crowds clogged the streets and caused traffic jams in some parts of Beirut as they tried to get to neighbourhoods thought to be safer, witnesses said.
A worker cleans a street as smoke rises from a destroyed building in Beirut, Lebanon. (AP PHOTO)
"Residents of Lebanon, the IDF (Israeli military) will begin attacking infrastructure belonging to the Hezbollah Al-Qard Al-Hassan Association - get away from it immediately," the Israeli military's spokesperson said on X.
Al-Qard al-Hassan - which the US has said is used by Iran-backed Hezbollah to manage its finances - has more than 30 branches across Lebanon including 15 in densely populated parts of central Beirut and its suburbs.
There was no immediate statement from the organisation, Hezbollah or the Lebanese government.
Asked by journalists whether the branches could be considered military targets, a senior Israeli intelligence official said: "The purpose of this strike is to target the ability of Hezbollah economic function both during the war but also afterwards to rebuild and to rearm ... on the day after."
Cross-border fighting between Israel and Hezbollah erupted a year ago when the group began launching rockets in support of Palestinian militant group Hamas in Gaza.
At the start of October, Israel launched a ground assault inside Lebanon in an attempt to stabilise the border region for its citizens who had fled rocket attacks in northern Israel.
Israel has intensified its military campaigns both in Gaza and Lebanon, days after the killing of Hamas leader Yahya Sinwar raised hopes of an opening for ceasefire negotiations to end more than a year of conflict.
With US elections approaching, officials, diplomats and other sources in the region say Israel is seeking through military operations to try to shield its borders and ensure its rivals cannot regroup.
Israel is also preparing to retaliate for an Iranian missile barrage earlier this month, though Washington has pressed it not to strike Iranian energy facilities or nuclear sites.
Earlier on Sunday Israel said it hit Hezbollah's intelligence headquarters and an underground weapons workshop in Beirut.
Fighter jets killed three Hezbollah commanders, the Israeli military said.
Hezbollah made no immediate comment on those strikes, but said it had fired missiles at Israeli forces in Lebanon and at a base in northern Israel.
Flames and smoke rise form an Israeli airstrike on Dahiyeh, a southern suburb of Beirut, Lebanon. (AP PHOTO)
The strike came two weeks into a major assault around Jabalia, just south of Beit Lahiya, where Israel says its troops have been trying to root out remaining Hamas fighters.
Israel said the strike hit a Hamas target, questioning an earlier death toll of 73 released by the Hamas media office.
Hamas-led militants killed 1200 people and took 250 hostages in the attack on Israel on October 7 2023 that sparked the war in Gaza, according to Israeli tallies.
Israel's military response in Gaza has left more than 42,500 people dead and has made most of Gaza's 2.3 million people homeless, Palestinian officials say.
Over the past year, Lebanese officials estimate that more than 2400 people have been killed and more than 1.2 million people displaced in Lebanon. Fifty-nine people have been killed in northern Israel and the occupied Golan Heights over the same period, Israeli authorities say.
