"We strongly call on all sides involved to show restraint and avoid all acts that could lead to complicating the situation further," the Russian foreign ministry said in a statement.

"It is absolutely unacceptable to create threats to the lives and security of Russian soldiers that are in the Syrian Arab Republic on the invitation of the legal government to assist in the fight against terrorism," it added.

The foreign ministry said it had "interpreted the latest developments and attacks on Syria with serious concern" and said that the human and material losses on the Syrian regime's side are not yet known.

Israel struck targets inside Syria on Saturday after intercepting what it said was an Iranian drone entering its airspace from Syria, which it labelled an "attack."

The Russian foreign ministry did not mention Moscow's earlier joint statement with the Syrian regime's other allies -- Iran and Lebanese group Hezbollah -- that called Israeli claims of the Iranian drone in its airspace "lies."

Russia became involved in the multi-front conflict in September 2015, when it began an aerial campaign in support of President Bashar al-Assad's military.

Israeli Prime Minister Benjamin Netanyahu held talks with Russian President Vladimir Putin last month on Iran's influence in war-torn Syria and in Lebanon, seeking to persuade Russia to limit Iran's presence near Israeli territory and to stop it from entrenching itself militarily in Syria.

Putin ordered the partial withdrawal of Russia's troops from Syria in December, saying their task in the war-torn country had been largely completed.