Iran said it had yet to decide whether to attend a new round of peace negotiations with the United States on Monday, casting uncertainty on a push to stop the Middle East war from resuming.
US President Donald Trump said he was sending negotiators to Pakistan for talks on ending the war that engulfed the region and rattled global markets, while repeating threats to attack Iran's infrastructure if it did not make a deal.
After initial talks in Islamabad ended without a deal earlier this month, both sides have accused the other of breaching a temporary truce that is now in its final days.
"We have no plans for the next round of negotiation, and no decision has been made in this regard," Iranian foreign ministry spokesman Esmaeil Baqaei said Monday.
"The US is carrying out behaviors that do not in any way indicate seriousness in pursuing a diplomatic process," he added, calling an ongoing US blockade of Iranian ports and its recent seizure of a ship "clear violations of the ceasefire".
Trump has similarly accused Tehran of violating the truce -- set to lapse overnight Tuesday -- by firing on ships in the crucial Strait of Hormuz trade route, which Iran has all but shut.
Meanwhile, ISNA news agency cited a spokesperson for Iran's central command center as warning that the military "will soon respond and retaliate against this armed piracy", while Tasnim reported Tehran had sent drones in the direction of US military ships.
Iran's Revolutionary Guards for their part warned that any attempt to pass through the Strait of Hormuz without permission "will be considered cooperation with the enemy, and the offending vessel will be targeted".
Chinese President Xi Jinping told Saudi Arabia's Crown Prince Mohammed bin Salman in a phone call on Monday that "normal traffic" through the vital conduit for oil and gas shipments "should be maintained", state media said.
- Sticking points -
Iran's foreign ministry said delays in implementing a ceasefire in Lebanon, where Israel has been fighting militant group Hezbollah, were also a violation of the Middle East truce.
A separate ceasefire agreed between Israel and Lebanon took effect on Friday and included Hezbollah, whose rocket fire in support of Iran drew Lebanon into the war.
Israel's military on Monday warned Lebanese civilians against returning to dozens of villages in southern Lebanon, claiming Hezbollah's activities were violating the agreement.
Nonetheless, thousands of displaced residents have begun making their way back to southern Lebanon since the truce began.
Israeli Defense Minister Israel Katz said Sunday that the military would use "full force" against any threats in Lebanon, even during the ceasefire.
Hezbollah lawmaker Hassan Fadlallah told AFP on Monday his group would work to break the "Yellow Line" that Israel has established in southern Lebanon, even as he said it wanted "the ceasefire to continue".
Another major issue in the US-Iran negotiations has been Tehran's stockpile of enriched uranium, which Trump said on Friday it had agreed to hand over.
But Iran's foreign ministry has said the stockpile, thought to be buried from US bombing in last June's 12-day war, was "not going to be transferred anywhere".
Baqaei said on Monday that the issue was not discussed with US negotiators.
"It was never raised as an option for us," he said.
