The Justice Department ordered two leading Chinese state-run media organizations to register as foreign agents, according to people familiar with the matter, as U.S. officials ramp up efforts to combat foreign influence operations and toughen their stance on a variety of China policies.

The DOJ in recent weeks told Xinhua News Agency and China Global Television Network—known as CGTN now and earlier as CCTV—to register under a previously obscure foreign lobbying law that gained prominence when it was used in the past year against...