The U.S. Treasury has moved to further restrict Iran's access to the U.S. financial system, by banning certain money transfers.
The Treasury Department announced on Thursday that it will revoke Iran's so-called "U-Turn" license, which currently allows transfers to briefly enter the United States before being sent to offshore banks.
Until Thursday, U.S. banks were allowed to process certain money transfers for Iranian banks and other Iranian customers as long as the payments were initiated by and ended up in offshore non-U.S. and non-Iranian banks.
U.S. officials say the ban is aimed at increasing financial pressure on Iran to end alleged support of terrorist groups and nuclear proliferation.
Iran is under three sets of international sanctions. It has been accused by several Western countries of seeking nuclear weapons. Tehran says its nuclear program is solely for peaceful purposes.
Separately on Thursday, Israeli Foreign Minister Tzipi Livni said any U.S. talks with Iran may be seen as a sign of weakness.
The statement was Israel first official note of caution over Barack Obama's election as U.S. president. Mr. Obama said during the campaign he would be willing to hold talks with Iranian leaders.
The Israeli government fears it could be the target of an attack by strongly anti-Israeli Iran.
In a highly unusual move, Iranian President Mahmoud Ahmadinejad - one of Washington's harshest critics - congratulated Mr. Obama on his victory. He said he hopes the U.S. president-elect will change American policy, which he described as arrogant.
Some information for this report was provided by AFP and AP.