The United States is considering restricting imports of Venezuelan crude oil and exports of U.S. refined products to Venezuela, U.S. Secretary of State Rex Tillerson said on Sunday, to put pressure on socialist President Nicolas Maduro to "return to the constitution."

"One of the aspects of considering sanctioning oil is what effect would it have on the Venezuelan people? Is it a step that might bring this to an end more rapidly?" Tillerson said at a news conference in Buenos Aires, referring to Venezuela's economic and political crisis.

Tillerson, on a Latin America trip that also includes visits to Mexico, Peru, Colombia and Jamaica, raised eyebrows on Friday after he suggested that Maduro could be toppled by his own military.