The US has imposed sanctions on the Commercial Bank of Syria, forcing all US banks to sever ties with the group.
Syrian had already ordered its officials to make transactions in euros
The US Treasury Department said it had made the decision as the bank had been used to move terrorist cash and launder money from "illicit" Iraqi oil sales.
But the bank played down the move saying it would have little effect on its business.
The bank added that US banks had already been loosening their ties with it ahead of the official US decision.
Meanwhile, Syria's prime minister last month told all government departments to carry out their transactions in euros instead of dollars as a precautionary measure ahead of any possible US economic sanctions.
Syria added that the US had taken the decision for "political reasons" rather than it being based on "logical evidence".
In May, the Treasury Department issued a preliminary order over its concerns about the Syrian banks activities, the latest announcement makes that order final.
The ruling bars any US bank or financial group from for opening or maintaining an account at the state-owned bank or its subsidiary the Syrian Lebanese Commercial Bank.
However, the order does not freeze funds held in the US by the Syrian bank; those accounts are used by foreign banks to do business in the US if they do not have subsidiaries in the country.