US President Donald Trump said that Washington had "very good talks" regarding Iran after the two sides held an indirect dialogue in Oman, pledging another round of negotiations next week.
Iran for its part said it expected to hold more negotiations with the United States, hailing a "positive atmosphere" during a day of talks in the Omani capital.
With an American naval group led by an aircraft carrier in Middle Eastern waters, US and Iranian delegations held talks in Muscat on Friday mediated by Oman without publicly meeting face-to-face.
"We likewise had very good talks on Iran," Trump told reporters on board Air Force One en route to his Mar-a-Lago resort in Florida.
"We're going to meet again early next week," he added.
However, shortly after the talks concluded, the US announced new sanctions against shipping entities and vessels, aimed at curbing Iran's oil exports.
Trump also signed an executive order Friday enabling his administration to impose tariffs on goods from countries doing business with Iran, with any potential levies threatening trade with countries including China, Germany and the United Arab Emirates.
It was not clear if the moves were linked to the talks, which were the first between the two foes since the United States joined Israel's war with Iran in June with strikes on its nuclear sites.
While Iran warned against further threats after Washington raised the spectre of new military action, Trump said: "If they don't make a deal, the consequences are very steep."