The proposal was sent even as Washington began to move paratroopers to the Middle East to back up a contingent of Marines already heading there.
Iran's military scoffed at the diplomatic efforts and launched more attacks on Wednesday on Israel and the Persian Gulf region, including an assault that sparked a huge fire at Kuwait International Airport.
The Pakistani officials described the 15-point plan broadly as touching on sanctions relief, civilian nuclear co-operation, a rollback of Iran's nuclear program, monitoring by the International Atomic Energy Agency, missile limits and access for shipping through the Strait of Hormuz.
Iran's attacks on regional energy infrastructure and its chokehold on the Strait of Hormuz, a strategic waterway through which a fifth of the world's oil is shipped, has sent oil prices skyrocketing and rocked world markets over fears of a global energy crisis.
At least 1000 troops from the 82nd Airborne Division are expected to be sent top the Mideast in the coming days.
The Pentagon is also deploying two Marine units that will add about 5000 Marines and thousands of sailors to the region.
The moves are being framed as US President Donald Trump allowing himself "max flexibility" on what he will do next.
Trump has said American officials are in negotiations with Iran, though he has not said who they are in contact with.
Iran's united command of the military and Revolutionary Guard suggested there were no talks.
"Have your internal conflicts reached the point where you are negotiating with yourselves?" spokesman Ebrahim Zolfaghari said.
"Our first and last word has been the same from day one, and it will stay that way: someone like us will never come to terms with someone like you," he said in the video statement.
"Not now, not ever."
The White House did not respond to requests for comment.
The Israeli military announced it had begun new wide-scale attacks early on Wednesday on Iran targeting government infrastructure.
Missile alert sirens began early on Wednesday in Israel as Iran launched its own attacks, which have been a daily occurrence since Israel and the US attacked Iran on February 28 to start the war, which has killed thousands.
Iran also kept up the pressure on its Gulf Arab neighbours, with Kuwait and Saudi Arabia saying they had repelled fresh drone attacks.
Any talks between the US and Iran would face monumental challenges.
Many of Washington's shifting objectives, particularly over Iran's ballistic missile and nuclear programs, remain difficult to achieve.
Also, it's not clear who in Iran's government has the authority to negotiate - or would be willing to, as Israel has vowed to continue killing the country's leaders.
Mediators were pushing for a possible in-person negotiation between the Iranians and the Americans, perhaps as soon as Friday in Pakistan, Egyptian and Pakistani officials said.
However, that would require the Americans to immediately start travelling from the US to be there in time.
Iranian officials likely remain worried about the Israelis, whose air strikes in the war have killed officials up to supreme leader Ayatollah Ali Khamenei.
Iran is also highly suspicious of the United States, which twice under the Trump administration has attacked during high-level diplomatic talks, including with the strikes that started the current war.
Zolfaghari said that the US was in no position to negotiate: "The one claiming to be a global superpower would have already gotten out of this mess if it could."
Speaking Tuesday at the White House, Trump said the US was "in negotiations right now" and that the participants included special envoy Steve Witkoff, his son-in-law Jared Kushner, Secretary of State Marco Rubio and Vice-President JD Vance.
"And the other side, I can tell you, they'd like to make a deal," Trump said.
with Reuters
17°C