(COMBO) This combination of pictures shows Russia's President Vladimir Putin (L) and Iran's Foreign Minister Abbas Araghchi. AFP
"The US approaches caused the previous round of negotiations, despite progress, to fail to reach its goals because of the excessive demands," Araghchi was quoted as saying by Iranian state media.
He also said that "safe passage through the Strait of Hormuz is an important global issue", as the US and Iran continue their rival blockades in the waterway.
Araghchi arrived in Russia on Monday, where he is expected to meet with Russian President Vladimir Putin, as peace efforts between Tehran and Washington hung in the balance, following a flurry of regional diplomacy and the collapse of planned talks in Pakistan.
It comes after Araghchi visited Oman between trips to Pakistani capital Islamabad, as mediators push to keep peace talks between Tehran and Washington alive.
On Saturday, US President Donald Trump scrapped a planned trip to Islamabad by his envoys Steve Witkoff and Jared Kushner.
In a sign that efforts were ongoing, the Fars news agency said Iran had sent "written messages" to the Americans via mediator Pakistan outlining red lines, including nuclear issues and the Strait of Hormuz.
Fars said the messages were not part of formal negotiations, however.
US media outlet Axios reported on Sunday that Iran had sent a new proposal to reopen the Strait of Hormuz and end the war, with nuclear negotiations postponed for a later stage, citing a US official and two other sources with knowledge of the matter.
Iranian state news agency IRNA cited the report without denying it.
A ceasefire in the US-Israeli war with Iran has so far held, but its economic shockwaves have continued to reverberate globally.
Iran has sealed off the strait, cutting flows of oil, gas and fertiliser and sending prices soaring, raising fears of food insecurity in developing countries. At the same time, a US blockade of the strait is in place.
Hopes for a second round of talks in Pakistan had centred on the planned visit by Witkoff and Kushner, but Trump cancelled the trip after Iranian state television said Araghchi had no plans to meet US officials there.
On Sunday, Trump told Fox News that if Iran wanted the talks, "they can come to us, or they can call us".
Trump faces domestic pressure as fuel prices rise following Iran's closure of Hormuz, with midterm elections due in November. Polls show the war is unpopular among Americans.
Safe transit
Asked whether cancelling signalled renewed fighting, Trump said: "No, it doesn't mean that."
On Saturday, Araghchi met Pakistan's military chief Asim Munir, Prime Minister Shehbaz Sharif and Foreign Minister Ishaq Dar, before travelling to Oman and returning to Islamabad.
He later left for Russia for talks with senior officials, his ministry said.
Russian and Iranian state media confirmed Araghchi's talks with Putin, citing officials from their respective governments.
Araghchi himself posted on X that the talks in Oman had focused on ensuring safe transit through Hormuz, "to benefit of all dear neighbors and the world".
"Our neighbors are our priority," he added.
Iran's Revolutionary Guards said they had no intention of lifting their blockade, which has roiled energy markets.
"Controlling the Strait of Hormuz and maintaining the shadow of its deterrent effects over America and the White House's supporters in the region is the definitive strategy of Islamic Iran," the Guards said on their official Telegram channel.
The United States has imposed a blockade of Iranian ports in retaliation.
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