The Britain-Based Syrian Observatory for Human Rights said the killed included members of the "National Defence" forces, DPA reported.
It added that the Israeli strikes, which took place shortly before midnight (2100 GMT), hit posts east of the village of Khirbet al-Tin in the countryside of Homs.
The monitoring group said that an ammunition depot thought to belong to the Lebanese Shiite movement Hezbollah was also hit in the same area.
It further said that explosions occurred near the Dabaa Military Airport.
The official Syrian news agency Sana had first reported that Israeli fighter jets hit targets in Syria late on Tuesday night.
The agency cited military sources as saying that the rocket attacks hit central and southern areas of the country, without providing specifics.
According to a Lebanese security source, the Israeli planes used Lebanese airspace to also hit targets south of Damascus.
The Observatory confirmed that loud explosions were heard on the outskirts of Damascus International airport as well as near the air force battalion in the Dmeir region.
It added that explosions were heard in the provinces of Hama and Latakia.
So far, there has been no official comment from Israel.
Israeli strikes in Syria have been seen as an attempt to prevent Iran, one of Syrian President Bashar al-Assad's main allies, from building up its military influence in the region.