Schlumberger, the world's biggest oil services company, has promised the US government it will pull out of Iran when its existing work contracts expire.
That will not be until at least 2013, but is still viewed by US officials as a significant win in the campaign to pressure Tehran over its nuclear programme.
Schlumberger, which has its headquarters in Houston, has for years avoided US sanctions banning Americans from doing business with Iran's oil sector by being registered in Curacao.
But the EU's introduction of sanctions against transferring oilfield technology to Iran has forced the company to rethink.
"Our decision means that if nothing changes, we will ultimately end operations in Iran," Rod Nelson, the company's vice president of communications, told The Boston Globe.
Company documents indicated Schlumberger shipped spare parts to Iran from the US and Europe through Jebel Ali, the Globe reported. Re-exporting equipment from the UAE was not illegal as long as the company's Iranian workers did not request it be ordered on their behalf.
Mr Nelson said Schlumberger did not break any laws and decided voluntarily to withdraw from Iran. But the US justice department and Securities and Exchange Commission are investigating.