The Syrian Army says Israeli aircraft have struck what it described as a "scientific research center" northwest of the capital, Damascus.
The Syrian Army said two people at the center in Jarmaya were killed and five wounded in the strike early on January 30.
The Syrian Army announcement contradicted earlier reports that Israel had conducted an airstrike inside Syria near the border with Lebanon, hitting a convoy of trucks allegedly carrying weapons for the pro-Iranian Lebanese Hizballah.
The Israeli military and a Hizballah spokesman declined to comment, and Syria denied the existence of any such shipment.
Russia's Foreign Ministery said it was "deeply concerned" about the reports and seeking clarification.
Moscow said it would be a "violation of the UN charter" if it turned out to be true that Israel had targeted a Syrian research center.
Israel is concerned some of Syria's chemical-weapons stockpiles could end up in the hands of Hizballah or terrorist groups linked to Al-Qaeda.
On January 27, Israel moved two Iron Dome antimissile batteries to the north.
Based on reporting by dpa, AP, and Reuters