Mohammad Javad Zarif said in Greece on Thursday that an agreement with negotiators from the U.S., Russia, China, Britain, France and Germany is possible provided "people have their foot in reality, not in illusions."

But he warned that "excessive demands" would make an agreement difficult, even without a deadline.

Mohammad Javad Zarif, Iranian Foreign Minister, announced, "Well I believe that if the other side respects what has already been agreed upon in Lausanne in terms of the parameters for an agreement and tries to draft based on mutual respect and a comprehensive agreement with Iran that is sustainable, that can be balanced, and that can be considered a dignified, mutually respectful agreement, then we can meet any deadline. And if people insist on excessive demands, on renegotiations, then it would be difficult to envisage an agreement, even without a deadline."

"I am hopeful that this (nuclear negotiations) will, in fact, reach a final conclusion within a reasonable period of time. I believe in order to do that people need to be realistic. People need to have their foot in reality, not in illusions, and I tend to refrain from negotiating publicly, but I believe the terms of the agreement in Lausanne are rather clear so I would expect my negotiating partners to refrain from making excessive demands," Zarif added.