"It's hard to believe we wouldn't have concerns about a potential agreement on a system that's not interoperable with NATO and with a company that has U.S. sanctions against it," she said during her Tuesday press briefing in Washington.
Ankara in September voiced its support for a contract for a missile defense system with China Precision Machinery Import and Export Corp.
The U.S. government has sanctioned the Chinese company for ballistic missile sales to the Iranian and Pakistan governments.
U.S. Secretary of State John Kerry met Monday in Washington with Turkish Foreign Minister Ahmet Davutoglu. Both sides focused largely on Turkey's role as a NATO ally and its efforts in the international push for conflict resolution in Syria. Neither side mentioned the missile defense controversy in their public statements.
Psaki said the matter has "long been a concern" for the U.S. government.
The Chinese FD-2000 anti-missile system is a rival to the U.S. Patriot missile system.