President Donald Trump said Sunday that Iran had violated the ceasefire agreement with the U.S. by attacking ships in the Strait of Hormuz, and he repeated threats to attack Iranian energy infrastructure unless it accepts a deal to end the war.

“Iran decided to fire bullets yesterday in the Strait of Hormuz — A Total Violation of our Ceasefire Agreement!” he posted on Truth Social. “That wasn’t nice, was it?”

“We’re offering a very fair and reasonable DEAL, and I hope they take it because, if they don’t, the United States is going to knock out every single Power Plant, and every single Bridge, in Iran,” he continued. “NO MORE MR. NICE GUY!”

His comments came as faltering diplomacy between the two sides saw Iran reimpose an effective closure of the Strait of Hormuz on Saturday, citing a continued U.S. naval blockade of Iranian ports, just one day after declaring the waterway “completely open” under the current ceasefire.

As the two sides traded blame over alleged violations, they also appeared divided over the prospects for a second round of talks. Two senior administration officials told NBC News Sunday that Vice President JD Vance, special envoy Steve Witkoff and Jared Kushner are expected to travel to Islamabad, Pakistan, to continue negotiations with Iran.

Trump had said negotiators would arrive on Monday evening in Islamabad, which last weekend hosted direct talks between the two sides, with the current two-week ceasefire set to end on Wednesday.

However, Iranian officials have pushed back on the prospect of new talks. Iran’s state-run IRNA news agency denied reports of a second round of negotiations in Islamabad, saying there is “no clear prospect” for talks under current conditions. It cited what it described as excessive U.S. demands, shifting positions and the continued naval blockade, which Iran views as a violation of the ceasefire.

Trump said that Iran had targeted vessels from France and the United Kingdom, without providing further details. Maritime authorities on Saturday reported gunfire and a projectile strike involving Indian vessels in the strait. Iranian state media has confirmed that shots were fired near the two Indian ships to force them to turn back.

Iran’s semiofficial Tasnim news agency reported two more tankers, sailing under the flags of Botswana and Angola, were forced to turn back by Iran’s forces on Sunday.

Iran’s Islamic Revolutionary Guard Corps has warned vessels against trying to cross the strait, which it said would be considered “cooperation with the enemy,” adding that “any violating vessels would be targeted.”

U.N. Ambassador Mike Waltz told NBC News' "Meet the Press" of the planned talks: "We'll see what the Iranians decide to do. They can choose to be a responsible member of the international community, or they can continue to be a rogue regime that masters its own people and seeks to hold the world hostage with a nuclear weapon."

"Everything’s on the table," he said, suggesting that mixed messaging from Iran on the status of the strait was an indication of "real confusion on the Iranians’ part" and "discord within their ranks."

Iranian officials said Saturday that new U.S. proposals were under review. Iran’s Parliament Speaker Mohammad Bagher Ghalibaf said Saturday that progress has been made toward a peace deal, with some issues “concluded,” but he warned Iran still has a “complete distrust” of the U.S. negotiators.

Speaking on state TV on Saturday night, Ghalibaf, who also serves as Iran’s chief negotiator, said officials had “stated our demands firmly,” adding: “Some issues in the negotiations have been concluded, while others have not. There is still a distance to a final agreement.”

“There must be a guarantee that this cycle of war, ceasefire and negotiation will not be repeated,” he said.

Ghalibaf said the strait had been closed because the U.S. was only “partially implementing the ceasefire,” adding that it will remain closed if the “naval blockade against us continues.”

“If the ceasefire is not implemented, we will not continue negotiations, and we will start the war,” he said.

Trump convened a Cabinet meeting in the situation room Saturday morning to discuss the Strait of Hormuz and the situation in Iran, according to two U.S. officials with knowledge of the meeting.

He had earlier said that his administration was currently talking to Iran and that talks were going “very well.”

But Iranian President Masoud Pezeshkian said Sunday that Trump was seeking to deny Iran its “nuclear rights” and that Iran was trying to end the war “with full dignity.”

“If a human being does not defend himself, he is dead,” he said. “They attacked us, and we defended.”

The Trump administration said its blockade of Iranian ports remains in force, with more than 20 ships turned back since Monday.

Following a summit of 51 countries that was co-chaired by France and the U.K. on Friday, French President Emmanuel Macron and British Prime Minister Keir Starmer “called for the unconditional, unrestricted, and immediate re-opening of the Strait of Hormuz.”

They also announced a joint neutral mission to provide reassurance to merchant vessels in the region.