Israeli air strikes near Damascus send a clear message to Iran and Syria that it will not allow arms shipments to Hezbollah, pundits said, playing down fears it would spark a major response.

Although Israel maintained official silence on the strikes, one at dawn on Friday and the second about 48 hours later, a senior Israeli source said they had both targeted "Iranian missiles destined for Hezbollah".

If confirmed, it would be the third time this year Israel has bombed Syrian targets, drawing anger from Tehran and causing the Israeli air force to move to its highest level of alert in years, the source said.

Israel, he told AFP, would not hesitate to act again.

"Any time Israel learns about he transfer of weapons from Syria to Lebanon, it will attack."

Eyal Zisser, a Syria expert at Tel Aviv University, said the raids sent a clear message Israel would no longer allow the transfer of Iranian weapons to Hezbollah.

"If Israel did indeed act in Syria then the message to Bashar (al-Assad) is clear... We are not after you, we are after Hezbollah, after Iran," he said on army radio of the Syrian president who has been fighting a bloody two-year insurgency aimed at toppling his regime.

"Bashar understands this message."

The Jewish state has frequently warned it would not tolerate the transfer of chemical agents or advanced arms to Hezbollah, and although the weapons targeted would not have affected the strategic balance in the region, Israel was showing a tough new line, he said.

"Israel is actually changing the equation and saying: 'From now on, I won't allow what's being going on for 20 years -- the transfer of weapons (from Iran) to Hezbollah," Zisser said.

Israel was exploiting Assad's weakness to do what it was unable to in the past by "attacking Iranian weapons en route to Lebanon while they are still on Syrian territory," he said, describing it as an effective "blockade" on Hezbollah.

"That's the strategic meaning -- it's not about Syria, or Bashar, but about Hezbollah and Iran."

Tzahi HaNegbi, an MP from the ruling Likud party who is known as a close confidant of Prime Minister Benjamin Netanyahu, said Israel been warning for years it would not tolerate advanced arms reaching Hezbollah.

"Israel warned, even before the start of the Syrian civil war, that it will act to prevent the supply of advanced weapons to Hezbollah," he told army radio.

"What we want is mainly to ensure that with all the chaos in Syria, we don't see Hezbollah getting stronger... which could result in us being dragged into a conflict with Hezbollah in which we absorb losses as we did in the past because we didn't act in time to damage its growing capabilities."

Israel fought a major 34-day war with Hezbollah in 2006 which killed 1,200 people in Lebanon, mainly civilians, and 160 Israelis, mostly soldiers.

Despite fears the raids could spark flare-up, Israel did not appear to be gearing up for a major confrontation, although it shifted two batteries of its vaunted Iron Dome anti-missile system to the north.

And Netanyahu made no immediate move to cancel his five-day trip to China, but his office confirmed his departure had been "delayed by two hours" without confirming reports it was for a security cabinet meeting.

Although commentators largely ruled out any armed Syrian response, they warned Israel could be playing with fire.

"If we continue with this policy, it require caution," said Zisser. "The question is what Iran and Hezbollah will do over time in light of the new reality Israel is creating."

"We are not on the eve of a war, for the moment," said Giora Eiland, a former Israeli general and head of national security, noting it was "not in the interest of Assad or Hezbollah".

"The risk of war is low but we never know if reality is changing before our eyes," he said. "It may be that we're treading a very fine line."

The fall of the Assad regime would benefit Israel because it would halt weapons transfers, he said.

"It is now in Israel's interest to speed up the downfall of Assad who is being blackmailed by Hezbollah and Iran who demand that he continue transferring weapons to Hezbollah in exchange for their support in the civil war," he said.

"If Assad falls tomorrow... with all the problems this would cause, at least it would mean there would be no more transfers of weapons to Hezbollah."