If a US person is doing business in said country (necessarily using that countries' banking system) it would be a violation.

The conditions that would authorize the imposition of penalties have not been triggered. Yet.

investigate, block during the pendency of an investigation, regulate, direct and compel, nullify, void, prevent or prohibit, any acquisition, holding, withholding, use, transfer, withdrawal, transportation, importation or exportation of, or dealing in, or exercising any right, power, or privilege with respect to, or transactions involving, any property in which any foreign country or a national thereof has any interest by any person, or with respect to any property, subject to the jurisdiction of the United States;

So, a factory in China is the "property in which any foreign country...has any interest", and the President could block any transactions involving that property.