The district courts of the United States are vested with jurisdiction specifically to enforce, and to prevent and restrain any person from violating, any order or regulation made or issued under this subchapter. Any civil action authorized to be brought under this subsection shall be referred to the Attorney General for appropriate action, except that the Secretary is not required to refer to the Attorney General minor violations of this subchapter whenever the Secretary believes that the administration and enforcement of this subchapter would be adequately served by suitable written notice or warning to any person committing such violation.