Tehran is still reviewing Washington's response to its proposal, under which the Strait of Hormuz could be reopened within seven days, and could reply within days, Iranian Foreign Minister Abbas Araghchi said on Thursday, according to Iranian semi-official Tasnim news agency.
"The diplomatic process is still continuing," Araghchi said.
Tankers are facing a higher risk of attacks and intimidation as they try to get critical shipments through the Strait of Hormuz after Iran issued new warnings it would block routes that it has not authorized, sources said.
Last week already saw the biggest number of attacks on tankers in the key waterway since the Iran war began - cutting the number of vessels trying to get through to the lowest in more than two months.
Iran has now warned regional countries that any attempt to open new routes for oil exports would be considered hostile, a senior regional official close to Tehran told Reuters.
It was part of a plan agreed by both Iran's political leaders and its Revolutionary Guards, the official added.
'Iran has no intention of allowing control to slip from its hands'
"Iran has absolutely no intention of allowing control of the Strait of Hormuz to slip from its hands, and has plans ready to block routes that some regional countries have for exporting oil," a senior diplomat in the region briefed by Tehran told Reuters separately.
"This could involve missile and drone attacks on ships, or sending boats to scare ships away," the diplomat added. "It plans to continue this policy of fear and threats," he said.
In recent months, Gulf oil producers have rushed shipments of oil through channels that hug the Omani side of the strait before transferring the oil in open waters in the Gulf of Oman with aerial support from the US, sources have told Reuters.
In the latest incident in the past 24 hours, projectiles struck a tanker some 51 nautical miles off the coast of Qatar inside the Gulf, British navy agency UKMTO reported.
Maritime security sources said the Antigua and Barbuda-flagged chemical tanker Acers had been hit by multiple projectiles north of Qatar's Madinat ash Shamal with minor injuries sustained by its crew.
“The Acers strike raises the prospect of a wider combat area affecting approaches to Qatar, Bahrain, Saudi Arabia, Kuwait and Iraq,” maritime risk intelligence group Pole Star Global’s subsidiary Clearwater Dynamics said in a report on Thursday.
The vessel's operator, listed in shipping databases as Antigua and Barbuda-based Valvoria Shipping, could not be reached for comment.
"The recent spate of Iranian attacks seems to have dampened the appetite of shipowners to sail through the Strait," said Jakob Larsen, chief safety & security officer at shipping association BIMCO.
"The Iranian threat appears to have increased."