The action against Nobitex and several of its executives accused it of helping the government evade sanctions and finance militants.
The United States and Europe were at odds over the Trump administration’s decision to ease oil sanctions on Russia.
China told its independent refineries to disregard U.S. sanctions over their purchases of Iranian crude.
Describing the transfer of the crew from the MV Touska cargo ship back to Iran as a ‘confidence-building measure’ between U.S. and Iranian officials, Pakistan again plays a mediating role.
The measures aim to crack down on Iran’s shadow banking system and Chinese purchases of Iranian oil.
The Treasury Department also targeted a top independent Chinese refinery that it said was a major buyer of Iranian petroleum.
The Treasury secretary said that currency swap line would benefit both the United Arab Emirates and the United States.
The Trump administration has loosened restrictions on Russian oil exports since the war in the Middle East began to rattle energy markets in March.
President Trump pivoted after escalating threats. Israel also announced it had killed an Iranian commander leading efforts to block the Strait of Hormuz to almost all shipping traffic.
Republicans and Democrats alike have criticized the Trump administration’s moves, taken to stabilize oil markets rocked by the war with Iran, warning that it is benefiting two U.S. adversaries.