The U.S. International Trade Commission, an independent federal agency, issued a limited order stopping all imports and sales for AT&T models of the iPhone 4, iPhone 3GS, iPad 3G and iPad 2 3G. The versions targeted are more than a year old but are still solid sellers.
All such exclusion orders are sent to President Barack Obama, who has 60 days to review them. If he does not veto the order, it goes into effect.
"We are disappointed that the commission has overturned an earlier ruling and we plan to appeal. Today's decision has no impact on the availability of Apple products in the United States," Apple spokeswoman Kristin Huguet said in a statement.
Designed to be a trade panel, the ITC has become a popular venue for patent lawsuits because it acts relatively quickly and it can order import bans, which are more difficult to get from district courts.
Samsung said in a statement that the ITC decision "confirmed Apple's history of free-riding on Samsung's technological innovations."
"Our decades of research and development in mobile technologies will continue and we will continue to offer innovative products to consumers in the United States," it said.
Tuesday's ruling overturned a decision by ITC Judge James Gildea, who ruled in September that Apple did not violate patents at issue in the case, which was filed in mid-2011.
Apple was found to infringe on a patent that relates to 3G wireless technology and the ability to transmit multiple services simultaneously and correctly. It is essential to ensuring that the devices are interoperable.