The United States and three key European allies -- Britain, France, and Germany -- say they want to eliminate any confusion about what investment and business deals with Iran are permitted after the nuclear deal.
The U.S. and European Union lifted most sanctions on Iran in January after Teheran agreed to curb its nuclear program.
But some sanctions remain, including those related to human rights and terrorism issues.
Some businesses are still confused over what is and is not permitted and are withholding investment and trade with Iran.
The State Department says it is ready to provide guidance and speedy clarification.
But President Barack Obama said last month that Iran still has to do more to prove to global firms that it is a safe place in which to do business.