Israel and Hezbollah exchanged fire along the Lebanese border after a week of rising tensions, sparking fears of an escalation and prompting concern from world powers.
Lebanon's president on Monday said an Israeli drone attack on Beirut at the weekend was a "declaration of war" that justified a military response.
Hezbollah leader Sayyed Hassan Nasrallah said on Sunday the fall of two Israeli drones overnight in suburbs of Beirut dominated by the Iranian-backed group amounted to a very dangerous move.
Qusayr, a once bustling commercial hub in western Syria, has not seen any fighting since government troops, with the help of Lebanon's powerful Iran-backed Hezbollah group, drove out Sunni Muslim rebels six years ago.
Hezbollah will work with the Syrian state and Lebanon's General Security agency to help return Syrian refugees who want to go back home, its leader said on Friday, a project that critics see as premature in the absence of a peace deal.
Forces backed by a Saudi-led coalition have killed eight members of Lebanon's Hezbollah group in Yemen in battles with the Iran-aligned Houthis, the coalition said on Monday.
Saad al-Hariri was speaking after meetings with lawmakers over the make-up of the new coalition to be formed after a May 6 parliamentary election.
In a post-election speech last week Hariri said the party had been expecting a better result and there had been "gaps" in how it conducted its campaign, for which people would be held responsible.
Rebels accepted a deal with the Syrian government on Wednesday to evacuate their enclave near the city of Homs, a Hezbollah military media unit and a rebel official said.