U.S. Treasury Secretary Steven Mnuchin said on Tuesday that if China doesn't follow the United Nations sanctions approved on North Korea, he will seek new financial sanctions on Beijing to cut off access to the U.S. financial system.

Mnuchin told a conference broadcast on CNBC that China agreed to "historic" sanctions on North Korea on Monday in a UN Security Council vote.

"If China doesn't follow these sanctions, we will put additional sanctions on them and prevent them from accessing the U.S. and international dollar system, and that's quite meaningful," Mnuchin said.