Iran’s foreign minister said on Sunday that there was a “real chance” to reach an agreement with the United States over his country’s nuclear program, as long as Washington was prepared to end sanctions and recognize Tehran’s right to peaceful nuclear enrichment.

Even as the country’s American-educated foreign minister, Mohammad Javad Zarif, was making his comments on ABC’s “This Week,” his deputy in Iran, seeking to reassure hard-liners there, said Tehran would never fully trust the United States.

The dueling narratives underscored the complexity of any rapprochement between the two countries, despite a series of unexpected public and private exchanges in recent weeks culminating in a historic phone call Friday between President Obama and Iran’s president, Hassan Rouhani.

While Mr. Zarif is widely believed to have the backing of the country’s supreme leader to at least give negotiations a try, hard-liners among the Iranian leadership are watching warily and could try to derail an agreement.