Iran described U.S. proposals to end a month of war in the Middle East as "unrealistic, illogical and excessive" on Monday and unleashed more missiles on Israel, as oil prices rose further after Yemen's Houthis entered the conflict.
U.S. President Donald Trump issued another warning to Iran on Monday to open the Strait of Hormuz, a waterway used for shipping a fifth of global oil and liquefied natural gas supplies, or risk U.S. attacks on its energy infrastructure.
Iranian Foreign Ministry spokesperson Esmaeil Baghaei said Tehran had received messages via intermediaries indicating Washington's willingness to negotiate. This followed a meeting of the foreign ministers of Pakistan, Egypt, Saudi Arabia and Turkey in Islamabad on Sunday to discuss mediation efforts.
But Baghaei, criticising the U.S. proposals, told a press conference on Monday: "Our position is clear. We are under military aggression. Therefore, all our efforts and strength are focused on defending ourselves."
Meanwhile, a Pakistani security official said that at this stage it appeared unlikely there would be direct U.S.-Iran talks this week. "We are trying our best to make it happen as early as possible," the official added.
Baghaei also said Iran's parliament was reviewing a possible exit from the Nuclear Non-Proliferation Treaty, which recognises the right to develop, research, produce and use nuclear energy as long as nuclear weapons are not pursued.
Trump has cited preventing Iran obtaining nuclear weapons as one of the reasons for attacking Iran on February 28. Tehran denies it is seeking a nuclear arsenal.
On Sunday, Trump said the U.S. and Iran had been meeting "directly and indirectly". But he has also been sending more U.S. troops to the region and Iran has remained defiant, maintaining its blockade of the Strait of Hormuz.
In a social media post on Monday, Trump wrote: "Great progress has been made but, if for any reason a deal is not shortly reached, which it probably will be, and if the Hormuz Strait is not immediately 'Open for Business,' we will conclude our lovely 'stay' in Iran by blowing up and completely obliterating all of their Electric Generating Plants, Oil Wells and Kharg Island."