Apparently, you can only import them if you purchased them in Cuba, and carry them with you.
From the CBP web site:
Can I import or bring Cuban cigars into the U.S. for personal use?
Persons authorized to travel to Cuba may purchase alcohol and tobacco products while in Cuba for personal consumption while there. Authorized travelers may return to the United States with up to $100 worth of alcohol or tobacco or a combination of both. Products acquired in Cuba may be in accompanied baggage, for personal use only.
Purchasing Cuban-origin cigars and/or Cuban-origin rum or other Cuban-origin alcohol over the internet or while in a third country (i.e. not Cuba) remains prohibited.
This also applies to non-U.S. citizens who enter the country.
A non-U.S. person (i.e. not a U.S. citizen or resident) arriving in the United States is authorized to import Cuban-origin merchandise, other than tobacco and alcohol, as accompanied baggage provided the merchandise is not in commercial quantities and not imported for resale. See 31 CFR § 515.569. If the non-U.S. person is arriving in the United States from a trip that included travel to Cuba, the person also is authorized to import as accompanied baggage alcohol or tobacco products purchased or otherwise acquired in Cuba with a value not to exceed $100 for personal use only. See 31 CFR § 515.560(c)(3).