The manufacture and storage of nuclear bombs is "wrong", and the use of such weapons is forbidden by Islam, Iranian TV quoted Supreme Leader Ali Khamenei as saying.
"Although we have nuclear technology, Iran has firmly avoided it," Khamenei said as quoted by State TV.
In May, a year after Trump's notorious unilateral withdrawal from the Iranian nuclear deal, Tehran began scaling back on its commitments under the accord.
Last month, the International Atomic Energy Agency announced that Tehran had begun installing advanced centrifuges which would allow it to increase the enrichment levels of its uranium stocks.
In May 2018, the Trump administration unilaterally withdrew from the JCPOA, and began reintroducing tough banking and energy-related sanctions against Tehran. The US also threatened to slap secondary sanctions against any country buying oil from Iran.