Syrian Information Minister Mohsen Bilal said on Sunday that if Israeli forces mount a ground offensive against Lebanon and approach Syrian soil, his country would not stand by.
"If Israel invades Lebanon and enters it by land ... then we will not stand with our hands tied, " the Syrian Arab News Agency cited Bilal as saying in an interview with Spanish media.
Bilal criticized the United States for not committing itself to pressing Lebanon and Israel to achieve a quick ceasefire.
He also rejected Washington's accusation that Syria provided weapons for Hezbollah.
Syria, which supports the Lebanese Shiite group of Hezbollah, has condemned the ongoing Israeli attacks on Lebanon and called for an immediate ceasefire.
The United States and Israel have accused Iran and Syria of financing and arming Hezbollah, and demanded Syria exert pressure on Hezbollah to help secure the release of the two Israeli soldiers captured by the guerilla group in a cross-border attack on July 12, which sparked fierce Israeli air strikes.
Over the past few days, Israel has been carrying out ground incursions into south Lebanon in a bid to neutralize Hezbollah and remove the group from the border area.
The conflict has killed more than 360 Lebanese and 36 Israelis.