Iranian Foreign Minister Abbas Araqchi dismissed new US sanctions as a sign of desperation and said the expected measures would fail to defeat Tehran, Reuters reported.
US Treasury Secretary Scott Besant, who is due to hold a news conference on Monday, threatened to impose the "heaviest sanctions in history" of Iran.
Iran's economy is already under immense pressure from international sanctions, its infrastructure has been repeatedly hit and thousands have been killed in airstrikes against the Islamic Republic since the US and Israel launched attacks on February 28.
But Tehran remains defiant after nearly six months of war and has brought shipping to a virtual standstill in the Strait of Hormuz, refusing to allow unauthorized oil tankers to pass through a waterway that is vital to global oil supplies. The effective blockade of the strait has boosted global oil prices.
Describing what he described as "repeated scenarios", Araqchi said in a video posted on Telegram: "The fact that American leaders have switched from military operations to the same old plans shows that they are desperate."
He said Washington should talk to Iran respectfully to find "a solution based on justice and honor".
"We have never been afraid. "All their actions - whether blockades or other military moves they have taken - have failed, and this new problem of theirs will also fail," he said.
US President Donald Trump warned of economic consequences against any country that provides "any kind of lifeline to Iran", and Besant called on China to cooperate with Washington, which buys more than 80% of Iranian oil, according to 2025 data from the analytical firm Kpler. China has called for diplomacy.
Iran said Pakistani Army Chief Asim Munir would visit Tehran on Monday as part of efforts to restore peace and security in the region, but gave few details.
Pakistan is mediating the conflict, and a Pakistani government source said Munir would address the latest developments, including the US threat of new sanctions.
Trump said on Friday that Washington was watching "what's going on" in the conflict.
"They would like to make a deal, but I don't think they're ready to make the right deal," Trump said of Iran.
The US attacks have severely crippled Iran's economy and devastated its navy and air force, but Tehran maintains enough missile and drone capabilities to intercept oil tankers and attack regional rivals.
Iranian Parliament Speaker Mohammad Baqer Ghalibaf said on Saturday that Tehran had received "numerous messages" from neighboring countries about establishing new regional security and economic cooperation agreements.
Ghalibaf did not say which countries he was referring to. He accused the US of endangering the security of its allies in the region in the name of Israel, adding that an independent regional order would ensure peace and security.
Trump has yet to achieve the goals he set for himself at the start of the war, such as dismantling Iran's nuclear program - whose status remains uncertain given that UN inspectors have been banned since 2025 - and creating the conditions for Iranians to overthrow their spiritual rulers.
President Massoud Pezeshkian also called for a diplomatic solution.
"It would be better to end the war today, when we are strong and have dignity and the whole world recognizes our victory and emphasizes that America, contrary to all regulations, attacks our schools, hospitals and infrastructure and is hated in the world," the ISNA news agency quoted him as saying on Friday.