WASHINGTON (Reuters) - President Barack Obama announced new U.S. sanctions against Iran's energy, petrochemical and financial sectors on Tuesday that he said would further pressure the country for failing to meet international nuclear obligations.

In a statement, Obama said the United States remained committed to finding a diplomatic resolution to the standoff with Tehran but was committed "to hold the Iranian government accountable for its actions."

"If the Iranian government continues its defiance, there should be no doubt that the United States and our partners will continue to impose increasing consequences," he said. Obama has been criticized by Republican presidential challenger Mitt Romney for failing to act strongly enough to stop Iran from gaining a nuclear weapon.

(Reporting by Laura MacInnis; Editing by Will Dunham)