Israel's air force bombed a weapons depot in Syria's Homs province on Wednesday, adding to a series of strikes in recent weeks, according to a monitoring group.
The Britain-based Syrian Observatory for Human Rights said it was still unclear whether the depot belonged to the Syrian government or its Lebanese ally Hezbollah.
"Israeli planes fired rockets at an arms depot in the industrial zone of Hisyah, south of the city of Homs, the observatory's director, Rami Abdel Rahman, told AFP.
Syrian television reported "an aggression" by Israel in the region, adding that the national army had "responded".
The Israeli army refused to comment on the report.
Israel has acknowledged carrying out airstrikes in Syria since the outbreak of the bloody war in the country six years ago to stop arms deliveries to Hezbollah forces.
The Syria observatory said Israel had also struck an arms depot near the Damascus airport on September 22, and this month targeted a jihadist faction linked to the Islamic State group in southern Syria, killing at least 10.
Israel said last month it had attacked Syrian government artillery after fire from across the armistice line hit the Israeli-occupied Golan Heights, and warned it would step up such retaliation in the future.