Bashar al-Assad made the comments on Monday during an annual address to the military
The order came as Israel and Hezbollah fighters entered their 20th day of fighting in neighbouring Lebanon.
Travelers from Syria have reported that some reservists have been called up for military duty, a sign that Syria is concerned the fighting in Lebanon could spill over.
The Syrian government has not made any announcement about calling up reserves.
"The anniversary of the founding of the army comes this year in view of international circumstances and regional challenges that require caution, vigilance, preparation and readiness," al-Assad said in a statement carried by the official Syrian Arab News Agency.
He called on all branches of the armed forces "to intensify efforts in training and to work for more preparations and raise readiness," according to the statement.
"We must be aware that every effort and every drop of sweat exerted in training now will spare a drop of blood when the time comes," he said.
Syria so far has stayed out of the Lebanon conflict, but Israeli air strikes have increasingly come closer, with repeated raids on the Beirut-Damascus highway that links Lebanon and Syria.
"We must be aware that every effort and every drop of sweat exerted in training now will spare a drop of blood when the time comes"
Bashar al-Assad, the president of Syria
In a warning to Israel four days after the Hezbollah-Israel fighting erupted, Syria's government promised a firm and immediate retaliation for any possible Israeli attack on its territory.
Syria has fought several times with Israel, which captured the Golan Heights from Syria during the 1967 Mideast war and annexed in it 1981.
Al-Assad said Syria was determined to support Lebanon and would not flinch under international pressure.
"All the threatening cries by the forces of hegemony that is backing the aggression will not hold us from continuing the course of liberation and supporting our brothers and the (Hezbollah) resistance," he said.