Israel won't confirm nor deny responsibility for the explosion. But an Israeli government minister said "the incident in Syria" fits Israel's policy of trying to stop weapons from being shipped from Syria to Hezbollah in Lebanon.
Two Damascus residents heard a massive explosion near the airport in the Syrian capital, the pair told CNN.
The blast was so severe "a thud could be heard in Damascus city and surrounding areas," said Rami Abdulrahman, founder of the UK-based monitoring group the Syrian Observatory for Human Rights.
"A fire broke out in the area, but the cause of the explosion is still unknown," he said.
The state-run Syrian Arab News Agency
, citing a military source, said a military position southwest of the airport "was exposed to an Israeli aggression with several missiles fired from inside the occupied territories at dawn."
SANA did not say whether anyone was killed or hurt in the blast. But it said the explosion would not stop Syrian forces from fighting terrorists -- a broad term that the government also uses to describe Syrian rebels.
"This aggression, which comes as a desperate attempt to raise the morale of terrorist groups that are collapsing under the blows of our armed forces, will not deter us from continuing and crushing our war on terror," the military source said, according to SANA.
Incident 'compatible with Israeli policy'
Israel's Intelligence Minister Israel Katz seemed to back up claims that Israel was responsible for the explosion in an interview Thursday with Army Radio.
"I can confirm that the incident in Syria is completely compatible with the Israeli policy of operating to prevent the smuggling advanced weaponry from Syria to Hezbollah in Lebanon by Iran," Katz said.
"I don't want to go any further as is natural in these circumstances," he said. But this event is completely compatible with our declared policy, a policy which we carry out as the Prime Minister has said, at any moment that we receive intelligence that shows the intent to pass advanced weapons to Hezbollah."
When pushed by the interviewer about whether he was claiming responsibility for the attack, Katz said: "I did not say that, I said what I said."
Separately, a spokesperson for Israel Defense Forces told CNN the army had no comment on reports that Israel was responsible.
Hezbollah in Syria
Hezbollah is a Lebanese militant group and political party, funded and supplied by Iran.
The group is at odds with Israel over territory along the Lebanese-Israeli border. It also supports the Syrian regime, committing thousands of fighters to battle alongside President Bashar al-Assad's forces.
Israeli Prime Minister Benjamin Netanyahu confirmed last April that his country had struck Syria "dozens of times."
On Wednesday, Israel's Defense Minister Avigdor Liberman discussed the situation in Syria with Russia's defense and foreign ministers during a conference in Moscow, the ministry said.
Liberman had expressed his concern about Iran's use of Syria to smuggle weapons to Hezbollah. He said Israel would not allow the concentration of Iranian and Hezbollah forces on the Golan Heights border, the ministry said in a statement.
Regional involvement in Syria
Syria is now a hotbed of three major conflicts: the battle against ISIS, the war against rebels seeking Assad's ouster, and the fight against Iranian and Hezbollah forces in Syria.
Each conflict involves other countries.
Last month, Syria fired anti-aircraft missiles at Israeli military jets.
Syria said the Israeli jets struck a military site near Palmyra, but Israel said they targeted a weapons shipment to Iran-backed Hezbollah.
Netanyahu defended the Israeli strike. "When we identify attempts to transfer advanced weapons to Hezbollah and we have intelligence and it is operationally feasible, we act to prevent it," he said.
"Iran is trying to establish itself permanently in Syria, with a military presence on the ground and at sea, and also a gradual attempt to open a front against us on the Golan Heights," he said.
Russia, a longtime ally of the Syrian regime, said outside forces should avoid causing conflict in Syria. Russian presidential spokesman Dmitry Peskov echoed that sentiment Thursday when asked about the alleged Israeli strikes near the Damascus airport.
"It is necessary to respect the sovereignty of Syria and refrain from actions that lead to increased tensions in the region," he said.