An electrical fault caused a series of loud blasts early on Sunday near a military airbase outside the Syrian capital Damascus, a Syrian military source cited by state media and an Iranian official, reported Reuters.
An official in the regional alliance backing Syrian President Bashar al-Assad and a Britain-based war monitor had earlier attributed the blasts to Israeli missile strikes.
The state media cited a military source as saying there was no "Israeli aggression" directed at the Mezzeh airbase near Damascus, after the sound of explosions was heard across the Syrian capital.
There was no immediate comment from Israel.
Iran's state news agency IRNA quoted an unnamed Iranian military official based in Syria as saying that the blast was caused by "an electrical short-circuit in an ammunition depot" on the outskirts of Damascus.
The official in the regional pro-Assad alliance had said the blasts were caused by Israeli missile fire from across the Golan Heights frontier between the two countries and by Syrian air defences responding.
A war monitor, the Syrian Observatory for Human Rights, also attributed the blasts to Israeli strikes, and said the blasts led to deaths and injuries.
Israel has previously acknowledged having carried out air strikes in Syria aimed at degrading the capacity of Iran and its allies, including Lebanon's Shi'ite Hezbollah group, which are backing Assad in the country's seven-year civil war.
In May, it said it attacked nearly all of Iran's military infrastructure in Syria after Iranian forces fired rockets at Israeli-held territory for the first time in the most extensive military exchange ever between the two adversaries.