"We have retaliated but I have no further details about this", he said.
The IDF made it a point to say that the attack last night was done by Iranian Al Quds forces, and not by proxies.
In April 26 remarks to Congress, Mattis said: "We need to focus on what is in the best interest of Middle East stability and the threat that Iran poses".
"But I can say that in terms of our objective, we focused less on personnel and more on capabilities and hardware.to inflict long-term damage on the Iranian military establishment in Syria".
"This is going to have a profoundly negative impact on the willingness of the Europeans to work with us in the way that they have been for a very long time".
The event took place amid heightened tensions after the Israelis fired rockets on military positions in Qunaitera, and after rockets slammed Israeli military sites in the Israeli-occupied Golan Heights.
Separately, Israel is deeply concerned over Iran's presence in Syria, where Tehran, like Moscow, backs President Bashar al-Assad's regime.
"This is a direct action by Iran against the force of Israel", he told Newshub. A series of strikes over the last few months all blamed on Israel have struck Iranian assets in Syria and killed Iranian forces there.
If confirmed, the incident would be the first such rocket fire by Iranian forces in Syria towards Israel.
Russia's foreign ministry said it was "deeply disappointed" by Trump's announcement on Tuesday that the United States would pull out of the Iran deal, while Netanyahu strongly supported the USA president's "bold" move. Hours later, Israeli rocket rockets targeted a military base in Kisweh, a commander in the pro-Syrian government regional alliance said.More news: Fresh Ebola outbreak hits DR Congo
That attack killed 15 people, including eight Iranians, the Syrian Observatory for Human Rights said, though the commander said there were no casualties.
Israel seized 1,200 square kilometres (460 square miles) of the Golan Heights from Syria in the Six-Day War of 1967 and later annexed it in a move never recognised by the global community. Netanyahu has been a leading critic of the deal, saying it did not contain sufficient safeguards to prevent Iran from reaching nuclear-weapons capability or address Iran's other activities across the region or its long-range missile program.
While the United States' European allies fiercely opposed the USA walking away from the Iran deal, Israel applauded Trump's decision.
The tensions worry Russian Federation, which wants to stabilize Syria.
Israeli Prime Minister Benjamin Netanyahu has used the Victory Day celebrations in Russian Federation to push his idea that Iran is a threat.
It ignored Iran's role as the world's largest sponsor of state terror, its complicity in the killings of a half-million Syrians and its threats to destroy the state of Israel. Israel responded with a blistering wave of missile strikes early Thursday.
Israeli media is carrying reports of the country's military "bracing" for a "barrage of missiles" fired by Shia forces in Syria. He added that several of the "Iranian rockets" were "intercepted" by Israeli defences.
Syrian state television broadcast footage of its air defences firing at incoming rockets and playing patriotic songs.
Dozens of missiles were shot down by anti-aircraft systems in Syrian airspace.