Iran’s Ayatollah Ali Khamenei has crushed hopes of talks with the US at the United Nations this month, saying the countries would not meet “at any level”.
Mr Khamenei said this was the position of Iran's entire leadership and that "all officials in the Islamic republic unanimously believe" it.
The announcement on Iranian State TV has ended speculation about a possible meeting between President Donald Trump and his Iranian counterpart, Hassan Rouhani, during the coming UN General Assembly in New York.
"Iranian officials, at any level, will never talk to American officials ... this is part of their policy to put pressure on Iran ... their policy of maximum pressure will fail," state television quoted Mr Khamenei as saying.
Tension in the Arabian Gulf has escalated after a weekend attack on major oil sites in Saudi Arabia that the US says Iran is responsible for.
Preliminary findings of a Saudi investigation found the weapons used to strike Saudi Aramco’s Abqaiq oil-processing plant and the Khurais oilfield were Iranian-made.
Saudi Arabia's Foreign Ministry said later on Monday evening that the initial investigation into Saturday's strikes had indicated Iranian weapons were involved.
"The preliminary results show that the weapons are Iranian and we are currently working to determine the location," Arab Coalition spokesman Col Turki Al Malki said in Riyadh.
"The terrorist attack did not originate from Yemen as the Houthi militia claimed."
US Defence Secretary Mark Esper said the US was preparing a response to the attacks.
"The United States military, with our inter-agency team, is working with our partners to address this unprecedented attack and defend the international rules-based order that is being undermined by Iran," he said in a tweet.
Iran denied accusations it was to blame and said it was ready for "full-fledged war". The Houthis continue to claim they fired 10 drones at the Saudi installations.
At a news conference in Ankara alongside Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan, Iranian President Hassan Rouhani said: "The people of Yemen have been forced to respond – they are only defending themselves."
The UAE's Minister of State for Foreign Affairs Dr Anwar Gargash hit back at Mr Rouhani on Tuesday morning.
"The justification for the unprecedented terrorist attack on Aramco's facilities in view of the developments in the Yemen war is completely unacceptable," Dr Gargash said.
Also on Tuesday morning, members of the US Congress blasted Iran after the attack, but expressed wariness about US military action, especially before they have a clearer picture of who was behind it.
Mitch McConnell, the Senate's Republican majority leader, called it "a brazen attack" with significant implications for the global energy market and said he welcomed Mr Trump's preparation to potentially release oil from the Strategic Petroleum Reserve to stabilise markets if necessary.
"I hope our international partners will join us in imposing consequences on Iran for this reckless destabilising attack," Mr McConnell said as he opened the Senate.
Jim Risch, a Republican senator and chairman of the Senate Committee on Foreign Relations, warned of US retaliation in case of an attack on US troops.
"Iran should not underestimate the United States' resolve," he said. "Any attack against US forces deployed abroad must be met with an overwhelming response – no targets are off the table."
The Republican senator Rand Paul, another foreign relations committee member, said on CNN that any attack on Iran would constitute a "needless escalation".
