William Perry, who ran the Pentagon during the Clinton administration, told Iran's Islamic Republic News Agency in Berlin that a "positive" approach to the negotiations might bring about more progress toward a peaceful settlement.
Perry, 85, stressed he did not speak for the U.S. government and did not consider exchanging ambassadors or one-on-one negotiations between the two nations to be absolutely necessary to defusing the potential crisis.
"I am certainly in favor of direct talks, but I don't think it should be considered key to the issue because the Iranian nuclear program affects many nations besides the United States," he said.
Perry added he was hopeful about a peaceful solution now that the United States was back at the negotiating table and Russia and China were taking a more active role in the discussions.
Iran says its uranium enrichment program is for peaceful civilian purposes and not to make a nuclear weapon.