No. Actually, right now, if you are travelling to Iran, there are certain devices that you must get specific permission from the U.S. Government to carry with you into the country, because of the embargo.
Also, on a separate note, after doing a bit more digging, it seems that the current embargo law does require companies or individuals to specifically not sell to an individual if they suspect/know either that the device may/will be sent to Iran. So, from a certain point of view, the employee was following the policy correctly (assuming that he really did find out from her that she intended to send it to Iran). However, and this is a BIG however, the problem in this instance is not that he was following policy, but was the way he went about it. According to several reports that I found regarding this story, the employee profiled the teenaged girl because she was speaking Farsi, and not because he already knew her intentions. He interrogated her based upon the fact that he knew she was speaking Farsi.
So, I pose the question to you: The U.S. also has a trade embargo against Cuba, does that mean that every Spanish speaking person that comes in to an Apple store should be grilled to see if they intend to send their device to Cuba? Where do you draw the line?