美国及其3个主要欧洲盟国英国、法国和德国表示，他们希望澄清，按照伊朗核协议，在伊朗的哪些投资和经贸往来是被允许的。
德黑兰同意对其核项目加以限制后，美国和欧盟于今年1月取消了对伊朗的大部分制裁。
但一些制裁措施依然有效，包括与人权和恐怖主义有关的制裁措施。
一些企业仍不清楚制裁措施的限制范围，因此没有在伊朗投资，也未同伊朗做生意。
美国国务院说，准备提供相应的指导和及时的说明。
但奥巴马总统上个月指出，伊朗必须采取更多行动，向外国企业证明在伊朗做生意是安全的。
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.