TEHRAN - Iranian President Hassan Rouhani said Sunday that ongoing nuclear negotiations with world powers are a matter of "heart," not just centrifuges ahead of talks next week in Geneva.

Speaking to an economic conference in Tehran, Rouhani both countered hard-line critics worried Iran will give up too much while also attempting to signal his administration remains open to negotiation with the six-nation group leading the talks.

If "we are ready to stop some types of enrichment which we do not need at this time, does it mean we have compromised our principles and cause?" Rouhani asked.

He responded: "Our cause is not linked to a centrifuge. It is connected to our heart and to our willpower."

On Jan. 15, Iranian negotiators will meet in Geneva with officials from the U.S., Russia, China, Britain, France and Germany, hoping to hammer details out of a final deal. Iran reached an interim, one-year deal with world powers in November 2013 to freeze its nuclear program in exchange for the easing of some sanctions. Negotiators later agreed to extend talks until June 30, with hopes of reaching a rough deal in March. (AP)