It's also ordering personnel at the U.S. embassy in the capital city of Damascus to leave the country.
The precautions are being ordered after a brutal crackdown on anti-government forces.
On Monday, at least 11 people were killed in Daraa, the city at the center of the uprising against President Bashar Assad.
Meantime, hundreds of people have reportedly been detained across Syria. Human rights activists say many of the arrests occurred in Damascus.
A relentless crackdown since mid-March has killed more than 400 people across Syria, with 120 dead over the weekend, rights groups said.
Syria has banned nearly all foreign media and restricted access to trouble spots since the uprising began, making it almost impossible to verify the dramatic events shaking one of the most authoritarian, anti-Western regimes in the Arab world.
The head of the Syrian Observatory for Human Rights, Rami Abdul-Rahman, who provided the death toll of more than 400 people since the uprising began last month, said that figure did not include those killed in the raids on Daraa and Douma, a Damascus suburb. It also did not include the number of Syrian troops killed, he added.
The Associated Press contributed to this report.