U.S. State Department spokeswoman Victoria Nuland announced sanctions on Impire Shipping and company President Dimitris Cambis for helping Iran evade sanctions by "disguising the Iranian origin of crude oil by concealing the control of a vessel by the National Iranian Tanker Company."
Washington is targeting Iran's energy sector with sanctions to limit Tehran's financing for Iran's nuclear program.
The U.S. government accused Cambis of using front companies to obscure the ownership of eight vessels that were capable of carrying about $200 million worth of oil shipments each.
"We are lifting the veil on an intricate Iranian scheme that was designed to evade international oil sanctions," Treasury Undersecretary for Terrorism and Financial Intelligence David Cohen said in a statement.
Cambis told Bloomberg News he wasn't aware of the sanctions, describing the allegations as "very bad rumors created by our competitors."
U.S. Secretary of State John Kerry this week issued sanctions waivers to 10 European countries and Japan for reducing Iranian crude oil purchases.