The Iron Dome missile defense system intercepted several rockets and the others failed to reach Israeli territory, he said.
On Thursday Israel launched its heaviest attack on Syria since the start of the conflict, after accusing Iranian forces in the country of firing rockets at Israeli military positions in the Golan Heights, the Associated Press reported.
There is growing speculation that Iran's military adventure in Syria is interfering with Russia's agenda in the region.
French President Emmanuel Macron has also appealed for calm.
Russian and Iranian intervention in Syria's long-running civil war helped tilt the balance of power back towards Syrian President Bashar al-Assad.
The head of the Observatory, Rami Abdurrahman, said five Syrian soldiers, including two officers, and 18 militia fighters were killed. It was not immediately clear what was hit.
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We dropped too many points this season. "People said we had no chance, I will not criticise one of them because they were right". There are many circumstances for this but we have to accept the final result .
The strikes "caused human losses in a number of the targeted areas", it said, adding the death toll was likely to rise.
In last night's air raid on Syria Israel used more than 70 air-to-surface and tactical missiles, the Russian Defense Ministry said.
Israel responded with attacks on the missile sites and other targets in Syria, hitting nearly all of Iran's infrastructure in Syria, according to Liberman.
"The situation, unfortunately, is very acute. We hope that one day they will stop talking about the destruction of Israel", he said.
Russia's support for the Assad regime in Syria and its relationship with Tehran present worrying possibilities for Israel.
If confirmed, this would be the first rocket attack carried out directly by Iran against Israel.
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Iran's leader ominously warned his country might "start enriching uranium more than before". Other signatories to the accord say they are still committed to it and want it to continue.
He said that Israel was willing to give up everything, do everything, except swap its neighbors.
Israeli Defense Minister Avigdor Liberman said that the courageous leadership move would eventually cause "the terrible and cruel Iranian regime to collapse".
Israel's military spokesperson Lieutenant Colonel Jonathan Conricus said earlier that Israel had retaliated for an attack on its outposts in the strategic Golan Heights plateau.
There were no casualties in the attack, Israel military said.
In the early hours of Thursday morning, the IDF's Arabic-language Twitter account said its military was "moving" against Iranian targets in Syria and warned Damascus not to intervene.
The scale of Israeli rocket fire appeared to be far higher than in previous incidents and Damascus residents described seeing explosions above the city from air defence systems. It said "no hits were located" on Israeli territory.
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The Israeli newspaper Haaretz quoted an unidentified security official as saying Israel's attacks inside Syria were the most extensive since the two nations signed a disengagement agreement after the October war of 1973. Israel has tried to stay on the sidelines but has acknowledged over 100 airstrikes over the past seven years.
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