Iran live updates: Tehran has 'no plans' for new round of talks, spokesperson says

Iranian Foreign Ministry spokesperson Esmaeil Baghaei said Monday that Iran has not yet made any decision regarding a potential new round of peace talks with the U.S. in Islamabad.

"As of now that I am here, we have no plans for the next round of negotiations," Baghaei said in a press conference, as quoted by Iran's semi-official Tasnim News Agency.

Referring to the possible continuation of talks in Pakistan, Baghaei said, "We have clearly announced the red lines and unacceptable items from the beginning, and insisting on them will not change our principled positions."

Baghaei told reporters that the U.S. and Israel are to blame for the ongoing disruption in the Strait of Hormuz.

"The international community must hold these two actors accountable for making the region insecure," Baghaei said, adding that U.S. conduct "has shown that it is not serious about pursuing the diplomatic process."

Baghaei cited ongoing Israeli strikes in Lebanon, the U.S. blockade of Iranian ports and Sunday's seizure of an Iranian cargo vessel as "clear examples" of "aggressive acts."

Baghaei added that the repeated U.S.-Israeli strikes on Iran over the past nine months have undermined Tehran's trust in American diplomacy.

The spokesperson for Iran's Khatam al-Anbiya Central Headquarters -- the country's top joint military command -- said in a statement on Monday that Iran would respond to the U.S. "aggression" against an Iranian merchant vessel in the Gulf of Oman, Iranian state television reported on Telegram.

Iranian forces will take "necessary action" in response to the American seizure of the M/V Touska on Sunday, the spokesperson said.

The Iranian Military Headquarters said that the U.S. has broken the ceasefire after President Donald Trump announced that the U.S. Navy had attacked and seized an Iranian-flagged cargo ship in the Gulf of Oman.

The Iranian military claimed the move "violated the ceasefire and maritime piracy," according to the statement published on the Iranian state news outlet FARS.

"The aggressor America violated the ceasefire and maritime piracy by firing at an Iranian merchant ship in the waters of the Sea of Oman, disabling its navigation system, and landing a number of its terrorist marines on the deck of the vessel," the statement read.

The Iranian military said it would "soon respond and retaliate against this armed piracy by the US military."

President Donald Trump said in a post on his social media platform Sunday afternoon that the U.S. Navy had attacked an Iranian-flagged cargo ship in the Gulf of Oman and that U.S. Marines have taken custody the vessel.

"Today, an Iranian-flagged cargo ship named TOUSKA, nearly 900 feet long and weighing almost as much as an aircraft carrier, tried to get past our Naval Blockade, and it did not go well for them," Trump said in the post.

If true, it would appear to be the first instance of the U.S. attacking and seizing a merchant vessel since it instituted the blockade of Iranian ports.

"The U.S. Navy Guided Missile Destroyer USS SPRUANCE intercepted the TOUSKA in the Gulf of Oman, and gave them fair warning to stop," Trump wrote. "The Iranian crew refused to listen, so our Navy ship stopped them right in their tracks by blowing a hole in the engine room."

The president further wrote that "U.S. Marines have custody of the vessel," which he said is "under U.S. Treasury Sanctions because of their prior history of illegal activity. We have full custody of the ship, and are seeing what's on board!"

The move comes after Joint Chiefs Chairman Gen. Dan Caine warned that the U.S. would actively enforce the blockade on Iranian-flagged vessels around the globe.

"In addition to this blockade, the joint force through operations and activities in other areas of responsibility, like the Pacific area of responsibility under the command of Admiral Paparo, will actively pursue any Iranian-flagged vessel or any vessel attempting to provide material support to Iran. This includes Dark Fleet vessels carrying Iranian oil," Caine said in a Pentagon press conference Thursday.

-ABC News' Nicholas Kerr