The ruling by Venezuela's Supreme Justice Tribunal on Friday means Machado, a 56-year-old industrial engineer, cannot register her candidacy for presidential elections scheduled for the second half of 2024.
"The United States is currently reviewing our Venezuela sanctions policy, based on this development and the recent political targeting of democratic opposition candidates and civil society," State Department spokesman Matthew Miller said in a statement.
The United States eased economically debilitating oil sanctions on the crude-exporting country in October after President Nicolas Maduro's government signed a deal with the opposition under which Caracas made commitments to hold a free and fair 2024 presidential election.
Miller said the court ruling was a "deeply concerning decision" that ran contrary to the commitments made by Maduro to allow all parties to select their candidates for the presidential election.
Maduro on Thursday said the deal with his opponents was in danger of collapse after what he has described as "conspiracies" against him.
Gerardo Blyde, head of the opposition negotiating team, denied members had been linked to acts of violence and demanded the court ruling be reversed.
"We are not asking for sanctions, that is not our job. We are looking for the process to move forward," he told a news conference in Caracas on Saturday.
(Reporting by David Ljunggren in Ottawa and Aida Pelaez-Fernandez in Mexico City;Editing by Diane Craft)
