John Glaser addresses the claim in "Four Emerging Myths about the P5+1, Iran Deal":
This ignores the record. Iran offered the U.S. an even better deal back in 2003 and they were rebuffed by a recalcitrant Bush administration who chose to isolate and sanction Iran instead of respond to diplomacy. In response to increasing U.S. sanctions, Iran’s enrichment program expanded and intensified. In 2003, Iran had 164 centrifuges operating and no 20% enriched uranium. After a decade of escalating sanctions, in 2013 Iran had 19,000 centrifuges and a sizable stockpile of 20% uranium. Only when [Hassan] Rouhani was elected and Iran was engaged in secret negotiations with Washington with the prospects of peaceful compromise on the horizon did Iran halt its installation of new centrifuges and put enrichment on hold.