Hezbollah, closely allied with Syria and Iran, said it "expresses full solidarity with Syria's command, army and people."
Hezbollah did not mention any convoy in the statement but said the strike aimed to prevent Arab and Muslim forces from developing their military capabilities.
The Syrian military denied the existence of any weapons shipment and said a scientific research facility outside Damascus was hit by the Israeli warplanes. It said the target was in the area of Jamraya, northwest of Damascus and about 15 kilometers (10 miles) from the Lebanese border.
Maj. Gen. Abdul-Aziz Jassem al-Shallal, who became in December one of the most senior Syrian army officers to defect, told The Associated Press by telephone from Turkey that the targeted site is a "major and well-known" center to develop weapons known as the Scientific Research Center.
Al-Shallal, who until his defection was the commander of the Military Police, said no chemical or nonconventional weapons are at the site. He added that foreign experts, including Russians and Iranians, are usually at such centers.
Regional security officials said Wednesday that the targeted shipment included sophisticated Russian-made SA-17 anti-aircraft missiles, which if acquired by Hezbollah would enable the militants to shoot down Israeli jets, helicopters and surveillance drones. The officials spoke on condition of anonymity because they were not authorized to brief the media.
Israeli lawmaker Tzachi Hanegbi, who is close to the prime minister, said pinpoint strikes are not enough to counter the threat of Hezbollah obtaining sophisticated weaponry from Syria.
"Israel's preference would be if a Western entity would control these weapons systems," Hanegbi said. "But because it appears the world is not prepared to do what was done in Libya or other places, then Israel finds itself like it has many times in the past facing a dilemma that only it knows how to respond to," he added.