As of 0401 GMT Tuesday, the Iran government can no longer buy US banknotes and broad sanctions will be slapped on Iranian industries, including its rug exports.

Asked if Tehran would be able to evade the measures, Pompeo told journalists "the United States is going to enforce the sanctions," speaking en route to Washington after attending a security forum in Singapore.

Pompeo said heaping pressure on Tehran was meant to "push back against Iranian malign activity," saying Iranians "are unhappy with the failure of their own leadership to deliver the economic promises that their leadership promised them."

"The Iranian people are not happy, not with the Americans but with their own leadership," he said.

"This is just about Iranians' dissatisfaction with their own government, and the President is pretty clear, we want the Iranian people to have a strong voice in who their leadership will be."

The US walked out of the 2015 nuclear deal in May and is bringing back "maximum pressure" sanctions for most sectors on August 6, and the energy sector on November 4.