The suspension was a response to a New York court order to freeze up to 2.6 billion dollars in assets. The court said the funds are needed to pay damages to the families of people killed in the 1983 bombing of US Marine Corps barracks in Lebanon.
The court had ruled that the Iranian government was involved in the attack and the victims' families had sought damages from that government.
However, the plaintiffs later brought the case to a US federal court, which on Thursday supported an objection by Tokyo-Mitsubishi that the order was invalid.
The ruling came amid growing concern among Japanese firms over a negative impact from suspended transactions on their business, including crude oil imports.