Israel strikes on Syria killed 3 Iran-backed fighters: monitor
The Syrian Observatory for Human Rights, a UK-based organisation with an extensive network on the ground, was not immediately able to provide the casualties' nationalities.
Syrian state media had reported an "Israeli aggression" overnight against targets in the south of the country, adding that its anti-air defence system had intercepted most missiles.
Last month, Israel said it had hit about 50 targets in the neighbouring country in 2020.
The Israeli army has carried out hundreds of air and missile strikes on Syria since the civil war broke out in 2011, targeting Iranian and Lebanese Hezbollah forces as well as government troops.
The Jewish state rarely acknowledges individual strikes, but has done so when responding to what it describes as aggression inside Israeli territory.