Lebanon's President Joseph Aoun said on Friday that 13 state security personnel were killed in an Israeli strike on a governmental building in the southern city of Nabatieh.
In a statement, Aoun condemned continued Israeli attacks and said targeting state institutions would not deter Lebanon from defending its sovereignty.
Naim Qassem, head of Iran-backed armed group Hezbollah, called on the Lebanese state to stop giving "free concessions" to Israel, with the two governments due to begin negotiations next week to end the war that has left nearly 1,900 people in Lebanon dead.
The government banned Hezbollah's military activities at the beginning of the latest war with Israel in March and is moving towards bilateral negotiations with Israel despite the opposition of Hezbollah, which is represented in the cabinet and parliament.
The state-run National News Agency (NNA) said "enemy warplanes launched a series of heavy strikes" on Nabatiyeh, including one in the vicinity of the government complex hitting the State Security office.
An AFP photographer saw extensive damage at the site, where a fire was still raging.
- Diplomatic scramble -
As the government prepared for talks with Israel in Washington, outside the auspices of the US-Iran talks in Islamabad, Qassem called on officials "to stop offering free concessions" and described Israel's military campaign as a failure.
"The Israeli enemy has failed on the battlefield... It has been unable to carry out the ground invasion it repeatedly announced," he said, adding that "the resistance will continue until the last breath".
More than 300 people, mostly civilians according to a Lebanese military source, were killed in a wave of simultaneous Israeli strikes on Lebanon on Wednesday despite the announcement hours earlier of a truce between the United States and Iran, with Israel and the US saying it did not apply to Lebanon.
Iran has insisted on including Lebanon in its ceasefire negotiations with the US.
- Quiet in Beirut -
On Thursday afternoon, the Israeli military issued a warning of incoming strikes for large, densely populated areas of southern Beirut, but had not carried out the threat as of Friday, with a Western diplomat telling AFP Friday that European and Arab states are pressuring Israel to stop targeting Beirut.
The Western diplomat, who asked to remain anonymous in order to discuss sensitive matters, said on Friday that "there is ongoing diplomatic pressure from European states, Gulf states and Egypt on Israel to prevent renewed Israeli airstrikes on Beirut after 'Black Wednesday'".
Thursday's Israeli warning included areas home to major hospitals and the road to the country's only international airport.
Public Works and Transport Minister Fayez Rasamny said, in a statement carried by the state-run National News Agency (NNA) on Thursday, that he had "received assurances" from foreign diplomats that the airport and the road leading to it would be spared.
Meanwhile, Mohammad Zaatari, director of the country's largest public medical facility, Rafic Hariri Hospital, told AFP: "We have received assurances, including from the International Committee of the Red Cross that the hospital would not be targeted."
The World Health Organization on Thursday called on Israel to cancel its evacuation warning for the Jnah district of Beirut because around 450 patients were in the Rafic Hariri and Al-Zahraa hospitals in the district, including 40 in intensive care.
The Israeli military said on Friday it had "dismantled" more than 4,300 Hezbollah sites in Lebanon and killed "more than 1,400" Hezbollah fighters.
Hezbollah, for its part, claimed several rocket launches on northern Israel, as well as attacks on Israeli troops advancing in the border area.
Hezbollah also said it targeted a naval base in the southern Israeli city of Ashdod on Friday, far from the border, with missiles.