By Agence France-Presse
However, the official said Mnuchin has no plans for a separate meeting with Chinese officials to try to resolve the trade conflict that has led to an exchange of tariffs on tens of billions of dollars in trade between the two countries.
Finance ministers and central bankers from the Group of 20 leading economies are due to meet in Buenos Aires Saturday and Sunday, where Mnuchin "will respond to concerns on US trade policies," the official told reporters in a conference call.
Group of Seven officials on hand for the broader meeting will also hold a one-hour session during which they will again discuss "concrete action with regard to China and its economic aggression," the Treasury official said.
That includes subsidies China used to create excess steel production capacity "burdening workers around the world," as well as heavy reliance on state-owned enterprises and export credits, the official said.
President Donald Trump has taken an confrontational stance on trade policy, imposing steep tariffs on steel and aluminum, which angered allies and prompted swift retaliation, as well as 25 percent duties on tens of billions of Chinese goods, with more on the way.
Although Mnuchin recently testified to Congress that the administration is willing to reengage with Beijing to try to resolve the dispute, the Treasury official said no meeting was scheduled with his Chinese counterparts.
"The secretary has had substantial contact with Chinese officials so there's not the imperative at this meeting to have a formal bilateral," the official said.
The trade tensions are caused by China's policies that "have moved in a non-market direction over the years and creates problems for many countries," the official said.
The International Monetary Fund said this week the growing trade confrontation is the "greatest near-term threat to global growth" and in the worst case could cut a half point off world GDP.
Mnuchin will hold separate bilateral meetings with officials from France, Canada, Germany and Mexico, among others, while at the G20.
He also will stop in Brazil on his way to Argentina for meetings there.