The meeting comes after Tehran threatened “unimaginable damage” to Israel if it attacked Syria.
Iran has denied Israeli allegations that it supplied missiles to the Lebanese militant group Hezbollah.
Syria and Iran are close allies. Both support Hezbollah, whose capture of two Israeli soldiers provoked the current crisis in the Middle East.
No word has emerged about the content of the discussions between the Syrian president and Iranian foreign minister Manouchehr Mottaki.
The talks come after a fifth night of Israeli air strikes on Lebanon, in response to a Hezbollah attack in which the two soldiers were seized and eight more died.
Strong defence
Hezbollah has been firing barrages of rockets into Israel from southern Lebanon, striking towns deeper into Israel than it was previously thought capable of hitting.
The BBC’s Jonathan Marcus says Hezbollah has an unknown quantity of longer-range systems in its arsenal, most of which are Iranian-made.
But Iran has denied supplying missiles or personnel to the militant group, saying it only gives it political support.
Syria and Lebanon are under pressure from the United States and Europe to use their influence to reign in Hezbollah.
But leaders in both countries have strongly defended Hezbollah’s actions.
Iran’s supreme leader, Ayatollah Ali Khamenei, said in a speech on Sunday that Hezbollah would not be disarmed.
He described Israel as an “evil and cancerous being”.
The BBC’s Heba Saleh in Damascus says Iran and Syria have a strong strategic alliance, based on what they see as their resistance to America’s attempts to impose its agenda on the region.
Diplomats in Syria say the country feels strengthened by Tehran’s support and knows that the US would want to prevent a wider conflict involving Iran, our correspondent says.
