Iran's supreme leader, Ayatollah Mojtaba Khamenei, vowed ​on Saturday to avenge the killing of his father and predecessor in his first message since Ayatollah Ali Khamenei's burial."We pledge to avenge ​the blood ​of ⁠the martyred leader and all the ​martyrs of these ​two ⁠wars from the criminal and disgraced killers," Mr Khamenei said in a written statement. He said revenge was "the demand of ​the nation" and "must ​certainly" take place.The former supreme leader was killed in the first wave of US-Israeli strikes on Iran in late February. The Iranian regime held a week of public funeral ceremonies for the late leader in cities across Iran and Iraq before he was buried in Mashhad on Friday.Mr Khamenei's message came amid heightening tension with the US and renewed fighting. It also coincided with a visit by Iranian Foreign Minister Abbas Araghchi to Oman on Saturday for talks on the Strait of Hormuz, as a fragile regional ceasefire hangs in the balance. Mr Araghchi was to meet Oman's Foreign Minister Badr Al Busaidi to discuss "establishing appropriate mechanisms for the safe transit of ships" through the shared waters, Iranian state media said. The visit follows prior consultations between the neighbouring countries on navigation through the strategic waterway, held in line with an interim agreement between Iran and the US, Iran's semi-official Tasnim ⁠news agency added. Attacks on commercial shipping vessels in the Strait of Hormuz last week, blamed on Tehran, prompted the US to carry out strikes and reimpose sanctions on Iran, with the two sides trading accusations of breaching the agreement.'A mistake'US media reported that Iranian officials privately told Mr Trump's advisers they "made a mistake" in shooting at commercial ships in the Strait of Hormuz last week and that the attacks stemmed from an "errant" sect of hardliners who were trying to undermine negotiations.Tehran also said it wanted to resume talks as agreed by both sides under an interim ceasefire last month, US officials reportedly told CBS News. US officials said Washington was expecting Iran to issue a statement acknowledging the Strait of Hormuz was open.If Iran did not issue the statement and did not adhere to it, “we’re not going to have a good outcome for them," they told reporters.US President Donald Trump on Friday said he had directed his administration to continue talks with Iran but that he still considered the ceasefire to be over. He first declared the end of the truce on Wednesday, a day after the US resumed deadly strikes on Iran in response to attacks on three ships in the Strait of Hormuz. Play00:44Iran accuses US of violating ceasefire agreementThe US on Friday also imposed new Iran-related sanctions, aimed at a key financier for Mr Khamenei, ​and 13 other individuals and entities, following Tehran's renewed attacks on oil tankers in the Strait of Hormuz, the Treasury Department said.US State Department spokesman Tommy Pigott said the sanctions aimed to cut off the Iranian regime's "financial lifelines". Mr Araghchi said on Saturday the sanctions were a breach of the interim agreement between Washington and Tehran."Iran has so far kept its word, unlike the so-called US Treasury Secretary who is violating Para 9 of the MoU," wrote Mr Araghchi on X on Saturday. "That violation follows other violations and missteps by the United States," he added.Paragraph 9 of the agreement stipulates that the US is not to impose new sanctions or deploy additional forces to the region.Iran's Foreign Ministry spokesman Esmaeil Baghaei has also accused Washington of breaching the agreement by launching attacks on Iran and revoking its oil sales licence and imposing additional sanctions. “If the other side violates its commitments, which it has, the Islamic Republic of Iran will take the necessary action, and it has done so. This approach will continue in the future,” he said in a televised interview.Mr Baghaei also denied that Tehran had requested negotiations with the US, but said it accepted a visit by mediators to Iran. Qatari ​negotiators ​were ​in Iran ⁠on Friday for talks to de-escalate ⁠tension and create conditions for broader negotiations to ⁠continue, Reuters reported. A source told the news agency that the talks were being conducted in co-ordination with the US.