Except as provided in this section, the President shall prohibit the opening, and prohibit or impose strict conditions on the maintaining, in the United States of a correspondent account or a payable-through account by a foreign financial institution that the President determines has, on or after the date that is 180 days after January 2, 2013, knowingly facilitated a significant financial transaction on behalf of any Iranian person included on the list of specially designated nationals and blocked persons maintained by the Office of Foreign Assets Control of the Department of the Treasury (other than an Iranian financial institution described in subsection (b)).