Moscow has announced it is ready to sell new weapons to Syria, triggering alarm from Israel, BBC reported.
Russian Foreign Minister Sergei Lavrov said any arms sales of "a defensive character" would not change the strategic balance in the Middle East.
But Israel's foreign minister said such sales could destabilise the region.
The comments came as Russian President Dmitry Medvedev and Syrian President Bashar al-Assad met at Russia's Black Sea resort of Sochi.
Moscow and Damascus are reportedly preparing deals on anti-aircraft and anti-tank missile systems, as well as surface-to-surface Iskander missiles.
Tzipi Livni, Israeli foreign minister, told a news conference in Jerusalem: " Russia has its own interests in the region and nobody wants to destabilise the region.
"And I think according to this assessment it is of mutual interest of Russia, Israel and pragmatic leaders of states in the region not to send this kind of long-range missiles to Syria."
She also said Syria was linked to Iran, Lebanese militant group Hezbollah and Palestinian militants Hamas.
Before the talks in Sochi, Syria's president had spoken of the need to speed up military and technical co-operation with Russia.
Syria was a close ally of the Soviet Union during the Cold War.
Relations between Moscow and Damascus have been getting closer recently - this visit is Mr Assad's third to Russia in three years.
Mr Assad said on Thursday Russia's military campaign in Georgia was a justified response to provocation from Tbilisi.
Russia has been strongly criticised by the West for its military operations in Georgia launched earlier this month.