Pompeo said that as part of a "maximum pressure campaign", the US was imposing sanctions against the Chinese company Zhuhai Zhenrong and its Chief Executive Youmin Li, accusing them of violating US law by accepting crude oil from Iran.
"We can't tolerate more money going to the ayatollah...," he said during a speech at the 120th Annual Convention of Veterans of Foreign Wars in Orlando on Monday.
The US Department of Treasury included Youmin Li and the company he runs on its Iran-related Specially Designated Nationals List on Monday.
In May 2018, the US announced that it was withdrawing from a multilateral nuclear deal with Iran because Iranian authorities were violating the spirit of the treaty with the purpose of secretly developing nuclear weapons.
In November 2018, it reinstated sanctions on the export of Iranian crude oil, although it granted China, the country's main oil buyer, a six-month exemption in order to find alternative suppliers.
Monday's announcement marks an escalation of tensions between Washington and Tehran after several attacks on ships, the shooting down of a US drone and the seizure by Iranian forces of a British tanker in the Persian Gulf last week.
US President Donald Trump said on Monday that he was seeing it increasingly difficult to reach an agreement with Iran that would make it possible to lower the escalation of tension between the two countries because, according to him, Tehran "disrespected" Washington.
"They disrespected the US. They should not have done that. ( ) Frankly, it is getting harder for me to want to make a deal with Iran (...) It could go either way very easily. And I am okay either way it goes," Trump said at the beginning of his talks with Pakistan Prime Minister Imran Khan at the White House on Monday.
The President made these statements shortly after accusing Iran on Twitter of lying about having arrested 17 Iranian citizens working for the Central Intelligence Agency.
"The report of Iran capturing CIA spies is totally false. Zero truth. Just more lies and propaganda (...) Iran is a total mess!" Trump tweeted.
( With inputs from IANS )