Hezbollah chief Hassan Nasrallah vowed Friday that Israel will pay "with blood" for civilians it killed in Lebanon this week, warning the group has missiles that can reach anywhere in Israel.

"The enemy will pay with blood" for every woman and child killed in Lebanon by cross-border fire, Nasrallah said in a televised address.

He warned that his Iran-backed movement has "precision-guided missiles that can reach... Eilat", on Israel's Red Sea coast, well beyond the northern towns it usually targets in retaliatory strikes.

Hamas ally Hezbollah and its arch-foe Israel have been exchanging near-daily fire across the border since the Israel-Hamas war broke out on October 7.

In the bloodiest day for Lebanon since then, the Israeli military said it had killed Hezbollah commander Ali al-Debs, his deputy and another fighter in Nabatiyeh on Wednesday.

The strikes also killed 10 civilians -- seven from the same family -- and two other Hezbollah fighters, according to an AFP tally based on figures released by the emergency services.

Nasrallah said the killing of civilians was aimed at "putting pressure" on Hezbollah to stop attacks on Israel, but stressed that the group will intensify its cross-border fire.

"The response to the massacre must be to pursue the resistance (against Israel)" and Hezbollah will not just strike "(military) positions... and spying equipment" as it has done before, he said.

The Israeli army said it carried out Wednesday's strikes after a soldier was killed by rocket fire from Lebanon.

Hezbollah retaliated with a barrage of rocket fire at the northern Israeli town of Kiryat Shmona, saying it was a "first response" to the deadly Israeli strikes.

- 'Rules of war: protect civilians' -

Israel hit back with new strikes on south Lebanon on Friday that killed five fighters from Hezbollah and the allied Amal movement, the groups said.

Lebanon's state-run National News Agency said Israeli warplanes hit five southern villages overnight.

Hezbollah said it carried out five attacks against Israeli military positions along the border.

Amal, headed by the speaker of the Lebanese parliament, Nabih Berri, said the funeral of the seven family members killed in Nabatiyeh would be held on Saturday.

The latest uptick in violence has caused international alarm, with fears growing of another full-blown war between Israel and Hezbollah like that of 2006.

The UN peacekeeping mission in Lebanon (UNIFIL) urged "intensified" diplomatic efforts "to restore stability and safeguard the safety of civilians" following Wednesday's bloodshed.

"The devastation, loss of life and injuries witnessed are deeply concerning," said UNIFIL spokesman Andrea Tenenti, urging "all parties involved to halt hostilities immediately to prevent further escalation".

UN humanitarian coordinator for Lebanon Imran Riza said "the rules of war are clear: parties must protect civilians".

Lebanese Prime Minister Najib Mikati, who condemned the latest deadly Israeli strikes, has said Beirut will lodge a complaint with the UN Security Council.

Since October, cross-border exchanges have killed at least 269 people on the Lebanese side, most of them Hezbollah fighters but also including 40 civilians, according to an AFP tally.

On the Israeli side, 10 soldiers and six civilians have been killed, according to the Israeli army.