The wary optimism in Dubai, traditionally a major hub for Iranian commerce, reflects a tantalizing prospect for businessmen across the world: that progress toward an agreement on Iran's nuclear plans could allow it to rejoin the global trading and financial system. 

This hope was created by the landslide election in June of Iranian President Hassan Rouhani, seen as a moderate, and fed by last month's resumption of high-level contacts between Tehran and Washington.

  "We are suggesting to our members that they should prepare for the possible removal of some of the obstacles to trade between the United Arab Emirates and Iran," said Hossein Asrar Haghighi, a founder of Dubai's Iranian Business Council. 

Some businessmen are making contingency plans to boost shipments to Iran if tensions ease further. "For example a trader buying a shipment of rice might get ready to increase it by 20 percent, and implement it depending on the situation."