GENEVA — Amid heightened tensions with the West over its nuclear program, Iran on Tuesday called for negotiations on a treaty banning nuclear weapons and condemned their production or possession as “a great sin.”

The Iranian foreign minister, Ali Akbar Salehi, said in a statement to the Conference on Disarmament here that there were two ways to engage with Iran on its nuclear program: engagement or confrontation. Iran, “confident of the peaceful nature of its nuclear program, has always insisted on the first alternative,” he said.

Mr. Salehi’s statement came only days after the United Nations’ nuclear watchdog agency expressed concern over the possible military dimensions of Iran’s nuclear program. The watchdog, the International Atomic Energy Agency, offered its assessment after Iran denied visiting inspectors access to military facilities linked to the nuclear program.

The agency reported in November that it had “credible” information that the complexes at Parchin, southwest of the capital, Tehran, included an explosives containment chamber used for experiments that were “strong indicators” of possible nuclear weapons development.