Washington is expressing strong opposition to re-engaging with Syria's Bashar Assad after UAE's foreign minister met with Syria’s once widely shunned president in Damascus on Tuesday.
The visit by Sheikh Abdullah bin Zayed Al Nahyan is the first by an Emirati foreign minister since Syria's civil war erupted in 2011. It comes as some Arab countries are improving ties with Syria.
"We will not normalize or upgrade our diplomatic relations with the Assad regime, nor do we support other countries normalizing or upgrading their relations, given the atrocities that this regime has inflicted on its own people," said State Department spokesman Ned Price.
Syria badly needs to boost relations with oil-rich countries as its economy is being strangled by crippling Western sanctions and it faces the task of post-war reconstruction.
It is not clear how Washington would react if the rapprochement between Syria and Gulf Arab countries extends to economic relations, given US sanctions on Damascus.
Most Gulf countries, at odds with regional rival Iran, seek warmer ties with Damascus, hoping to peel it away from Tehran.
The UAE is also home to thousands of Syrians who work in the Gulf nation and send money to their relatives at home.
Reporting by AP