"The Zionist entity (Israel) confirms through this despicable aggression, once again... its barbarism and wanton disregard for all international standards and laws," said a foreign ministry statement carried by state news agency SANA.

"The Syrian people... have never for a day forgotten (Nasrallah's) positions of support," the statement added.

Hezbollah since 2013 has openly backed the forces of President Bashar al-Assad in his country's civil war, which broke out after the repression of anti-government protests.

Israel has carried out hundreds of strikes in the country since the war began in 2011, mainly targeting army positions and Iran-backed fighters, including from Hezbollah.

Israeli authorities rarely comment on individual strikes in Syria, but have repeatedly said they will not allow arch-enemy Iran to expand its presence there.

Along with Russia, Hezbollah backer Iran has helped Assad regain territory lost earlier in the civil war.

While Damascus condemned Nasrallah's killing, in areas outside government control, some were celebrating, including in the Idlib jihadist-run rebel bastion.

Many Syrian opposition supporters and activists consider Hezbollah responsible for their woes, after the group fought Syrian rebels in a number of areas, leading to heavy losses among opposition factions and forcing tens of thousands of residents to flee, many to the country's northwest.