Britain ordered its financial institutions on Monday to halt all business with Iranian counterparts, including the central bank.
"We believe that the Iranian regime's actions pose a significant threat to the UK's national security and the international community. Today's announcement is a further step to preventing the Iranian regime from acquiring nuclear weapons," said British finance minister George Osborne.
U.S. President Barack Obama authorized on Monday to impose new sanctions targeting the Islamic republic's energy sector for the first time, saying the nation has chosen the path of "international isolation."
Obama signed an executive order authorizing sanctions on individuals who knowingly help Iran in its development of petroleum resources and the production of petrochemical products.
"New sanctions target for the first time Iran's petrochemical sector, prohibiting the provision of goods, services and technology to this sector and authorizing penalties against any person or entity that engages in such activity," he said in a statement, noting the moves "expand energy sanctions, making it more difficult for Iran to operate, maintain and modernize its oil and gas sector."
"As long as Iran continues down this dangerous path, the United States will continue to find ways, both in concert with our partners and through our own actions to isolate and increase the pressure upon the Iranian regime,"
In addition, the United States warned of the threats to governments or financial institutions that do business with Iranian banks, but stopped short of imposing sanctions on the banking sector in the Islamic republic.
Obama said it is the first time that the U.S. has ever identified the entire Iranian banking sector as a threat.