Syria vowed on Sunday a "Harsh and direct" response if it is attacked by Israel.
"Any aggression against Syria will have a firm and direct response not limited in time or means," Information Minister Mohsen Bilal said in a statement.
Syria is a main backer of Hizbullah, whose fighters captured Israeli soldiers in a cross-border operation on Wednesday, sparking Israeli reprisals that have so far killed more than 100 civilians in Lebanon.
Syrian President Bashar Assad said on Saturday that Syria will put its resources at the disposal of Lebanon to help cope with Israeli attacks devastating the country.
Meanwhile, Iranian Defense Minister Mustafa Mohammed Najjar said “should the Islamic world be forced to take military action, Israel will regret its crimes.
'There are no Iranian guards there'
The Fars news agency quoted Najjar as saying that “the US has dragged the entire region into a situation of war to ensure Israel’s security and to gain complete control of oil resources.”
Iran denied Israeli claims that it had troops in Lebanon and that it helped Hizbullah attack an Israeli warship, saying the guerrilla group could fend for itself without outside help.
“There are no (Iranian) guards there. Shipment of (Iranian) missiles to Hizbullah is also not correct,” Foreign Ministry spokesman Hamid Reza Asefi told reporters Sunday.
Israel said Saturday that 100 Iranian troops from the elite Revolutionary Guards were in Lebanon, and that they helped Hizbullah fire a sophisticated radar-guided missile at an Israeli warship blockading the Lebanese coast late Friday.