Allies of Damascus on Sunday threatened reprisals against any party that carries out "aggression" against Syria, two days after US missile strikes hit a Syrian airbase.
"The aggression against Syria oversteps all red lines. We will react firmly to any aggression against Syria and to any infringement of red lines, whoever carries them out," a statement from the Syria-based joint operations room for regime backers Russia, Iran and allied forces including Lebanon's Hezbollah.
"The United States knows very well our ability to react," said the statement published on the website of Al-Watan, a daily newspaper close to the regime.
On Friday, Washington carried out its first military action against Bashar al-Assad's government since the start of Syria's six-year war.
The cruise missile strike came after a suspected chemical attack on the rebel-held town of Khan Sheikhun on Tuesday killed at least 87 people, including many children.
"We condemn any attack targeting civilians and also condemn what happened in Khan Sheikhun, even if we are convinced it was a premeditated act by certain countries and organisations to serve as a pretext to attack Syria," Sunday's statement added.
Syria's war has killed more than 320,000 people since it started in 2011 with the brutal repression of anti-government protests.