Israeli anti-Iran airstrikes kill 23 troops, fighters in Syria
The UK-based Syrian Observatory for Human Rights said that an officer was included in those killed from regime troops, and that other casualties included Syrians and foreigners.
Thousands of Lebanese, Iranian and Tehran-backed Afghani, Pakistani and Iraqi fighters operate in Syria.
Russia's defence ministry said that Israel had used 28 planes in raids over Syria and fired a total of 70 missiles.
"[Twenty-eight] Israeli F-15 and F-16 aircraft were used in the attack, which released around 60 air-to-ground missiles over various parts of Syria," the ministry said in a statement.
"Israel also fired more than ten tactical ground-to-ground missiles."
Tel Aviv launched repeated rounds of rocket fire into Syria, targeting Iranian bases early Thursday after its military said Iranian forces in Syria had fired missiles at Israeli army positions in the Golan Heights.
Iranian forces in Syria reportedly fired around 20 rockets and missiles at Israeli army positions in the occupied Golan Heights.
The latest flare-up comes following US President Donald Trump's announcement on Tuesday that he was withdrawing from the landmark Iranian nuclear deal.
Both Russia and France have urged restraint, with French President Emmanuel Macron calling for a "de-escalation" in Syria.
Moscow similarly said they have established contact with all parties and have called for "restraint on all sides."
Germany, however, proportioned blame on Iran, and accused it of "provocation" after it fired a battery of rockets and missiles at Israeli army positions in the occupied Golan Heights.
"These attacks are a serious provocation that we strongly condemn. As we have always emphasised, Israel has a right to self-defence," said a German foreign ministry spokeswoman said in a statement.
She added that it is "crucial that there is no further escalation".