Treasury Secretary Steven Mnuchin said Friday he isn't worried about China selling its stockpile of U.S. Treasurys in retaliation over trade because there's plenty of demand for U.S. government bonds.

"If they decide they don't want to hold them, there are other buyers," Mnuchin told CNBC's Geoff Cutmore. "And, obviously, that would be very costly for them to do."

"They're looking at economics the way we're looking at economics, so it is not something I'm losing any sleep about," Mnuchin added in the interview from Bali, Indonesia, where the International Monetary Fund and the World Bank were holding their annual meetings.

Top White House economic advisor Larry Kudlow told CNBC on Thursday the White House was working on a meeting between President Donald Trump and Chinese President Xi Jinping at next month's G-20 summit in Argentina.

The leaders of the world's two largest economies will be getting together at a time when Washington and Beijing are locked in a trade war that's seen each side imposing tariffs on each other's products.