Iran on Monday said "intensive" exchanges were underway with Washington and offered to reopen the Strait of Hormuz under strict conditions, as efforts escalated to avert a return to war.
Foreign Minister Abbas Araghchi said indirect talks were taking place via mediators. China also urged a return to negotiations, while Iran's security chief discussed the conflict with Russian President Vladimir Putin.
Oil prices, sent rocketing by Iran's blockade of the Strait of Hormuz energy corridor, dropped more than six percent on Monday on optimism over the eight-month-old conflict.
"Given the sensitivity and gravity of the current situation, consultations and deliberations are very intensive," Araghchi said in a video interview with the official IRNA news agency.
"Qatar and Pakistan are playing a very active mediating role in these negotiations."
The Axios news outlet reported that US Vice President JD Vance had sent a letter to Iranian national security chief Mohsen Rezaei about possible new talks, marking the highest-level move in months.
The redoubled diplomatic push comes ahead of Tuesday's US midterm elections, where dissatisfaction over the war and higher fuel prices are weighing on US President Donald Trump's Republicans.
Democrats expect to win at least partial control of Congress and impose political constraints on Trump for the first time in two years.
Iran's First Vice President Mohammad Reza Aref said the messages received from the US were "an acknowledgement of our victory".
But Trump kept up his threats against Iran, telling a campaign rally that at "some point we're going to have to give them the hammer".
- 'Good-faith approach' -
A senior Iranian official said Tehran was ready to open Hormuz, the export highway for the energy-rich Gulf, within two days -- as long as Washington agrees to its list of demands.
In September, Iran proposed a seven-day plan to reopen the strait if the US agreed to demands including ending the war on all fronts, unfreezing Iranian assets, lifting oil sanctions and ending its counter-blockade of Iranian ports.
"The possibility of implementing this plan in two days is another indication of Iran's good-faith approach," foreign ministry spokesman Esmaeil Baqaei told reporters at a briefing.
"We have stated that, if Iran's demands are met, it would be possible to restore security to the Strait of Hormuz and resume the negotiating process within a short period."
Baqaei said "everything depends" on the US side accepting the Iranian demands. "Only then can we discuss the subsequent stages," he added.
Chinese President Xi Jinping discussed the war with Oman's Sultan Haitham bin Tariq in Beijing on Monday -- the first visit to China by the Gulf nation's head of state since diplomatic ties were established.
"The two sides called for resolving disputes through political and diplomatic means, urging the United States and Iran to pursue a peaceful path, achieve a ceasefire (and) prevent war entirely," an Omani statement said.
Beijing supports Tehran in "safeguarding its own sovereignty and security", Foreign Minister Wang Yi told Ali Bagheri, deputy secretary of Iran's Supreme National Security Council, according to a Chinese statement.
Bagheri told Wang that "Tehran's stance on defending its national security, sovereignty, and territorial integrity remains unchanged, and that Iran will make no compromises in this regard", according to state TV.
Russian President Putin also spoke with Iran's security chief Mohsen Rezaei about the war by telephone, Iranian state media said.
- 'Powerful response' -
In an interview with Al Jazeera released on Sunday, Araghchi said Washington must accept a new route agreed between Iran and Oman for transiting the strait.
He said the US must also remove sanctions imposed in recent months and reduce American troop numbers in the region.
Washington has since August rolled out a fresh raft of sanctions, part of what it called "economic asphyxiation" of Iran.
American and Israeli threats to Iran rose in the run-up to the midterms and last week's elections in Israel, where Prime Minister Benjamin Netanyahu failed to secure a majority.
On Saturday, Trump said he still had to "take care" of one or two targets including Pickaxe Mountain in central Iran, a suspected nuclear site which Tehran denies is such a facility.
"Any act of aggression against Iran, any military attack against Iran, by whatever means, will be met with a powerful, immediate and comprehensive response from us," Baqaei said.
