The Iranian official, speaking to Reuters, said Tehran was "positively reviewing" its participation in talks, despite earlier ruling them out, but stressed no decision had been made.
A Pakistani source involved in the discussions said there was momentum for talks to recommence on Wednesday and US President Donald Trump could attend in person, or virtually, if a deal were to be signed.
"Things are moving forward and the talks are on track for tomorrow," the source said on condition of anonymity.
Oil prices fell and stocks bounced back in early trading in Asia on Tuesday on the expectation that US-Iran peace talks will resume this week, after earlier meetings in Islamabad broke down without an agreement.
Oil prices had jumped about six per cent on Monday, trading on doubts over the talks.
Brent crude futures declined 54 cents, or 0.6 per cent, to $US94.94 a barrel and West Texas Intermediate for May fell $US1.11, or 1.2 per cent, to $US88.50.
But tensions remained high, with Iran's foreign ministry on Tuesday condemning the United States for an attack on the Iranian commercial vessel Touska at the weekend, demanding the immediate release of the vessel, its crew and their families.
"Iran would use all its capabilities to defend its national interests and security and protect the rights and dignity of its citizens ... the United States would bear full responsibility for any further escalation in the region," it said, according to Iranian state media.
Maritime security sources said on Monday the vessel was likely to have what Washington deems dual-use items that could be used by the military on board.
The US Central Command said Touska's crew failed to comply with repeated warnings over a six-hour period and the vessel violated an American blockade.
China, the main buyer of Iranian crude, has expressed concern over the "forced interception".
Iranian Foreign Minister Abbas Araqchi had on Monday said truce violations by Washington were a major obstacle to the diplomatic process, while top negotiator Mohammad Baqer Qalibaf accused Trump on social media platform X of increasing pressure through a blockade of Iran's ports.
He said Trump was deluded in seeking to "turn the negotiating table into a table of submission", adding Iran rejects negotiations under threat.
Thousands of people have been killed by US-Israeli strikes on Iran and in an Israeli invasion of Lebanon conducted in parallel since the war began on February 28.
Trump on Monday said Iran would negotiate but reiterated Washington would not allow Tehran to develop a nuclear weapon
"They're going to negotiate, and hopefully they'll make a fair deal, and they'll build their country back up, but they will not have - when they do it - they will not have a nuclear weapon," Trump said on the John Fredericks Media Network.
The United States has not specified when the two-week ceasefire will end. A Pakistani source involved in the talks said it would expire at 8pm Eastern time on Wednesday (10am Thursday AEST).
US Vice President JD Vance will travel to Pakistan on Tuesday for Iran talks, Axios reported on Monday, citing US sources.
White House Press Secretary Karoline Leavitt told Fox News the United States was close to a deal with Iran.
"Thanks to the success of the military operation and his (Trump's) hardline negotiating style, we're on the brink of a deal," Leavitt said.
"And if not, the president, as commander in chief, still has a number of options at his disposal that he's unafraid to use."
