Iran's Supreme Leader Ayatollah Ali Khamenei blamed the United States for instability in the Middle East and said Washington's fight against the Daesh terrorist group was "a lie".

"You [the United States] and your agents are the source of instability in the Middle East...who created [Daesh]? America ... America's claim of fighting against [Daesh]is a lie," Khamenei said in a meeting with high-ranking Iranian officials, according to his official website.

Iran and the United States cut diplomatic ties shortly after Iran's 1979 Islamic revolution and enmity to Washington has long been a rallying point for hardline supporters of Khamenei in Iran.

Khamenei has made several statements denouncing the United States since the start of the Muslim holy month of Ramadan, while U.S. President Donald Trump has spoken out against Iran in harsh terms since taking office, indicating that he will reverse the previous admistration's attempts at rapprochement with Tehran. Khamenei also said Iran had no intention of normalising ties with the United States.

"The American government is against an independent Iran ... They have problems with the existence of Islamic Republic of Iran...Most of our problems with them cannot be resolved," the semi-official Fars news agency quoted him as saying.

"America is a terrorist country and backs terrorism ... therefore, we cannot normalise ties with such country," he said.

Iran and the United States cut diplomatic ties shortly after Iran's 1979 Islamic revolution and enmity to Washington has long been a rallying point for hardline supporters of Khamenei in Iran. Since U.S. President Donald Trump took office in January, the yawning gap between Tehran and Washington has grown even wider with Trump's latest efforts to isolate Iran in the region, while bolstering cooperation with Saudi Arabia and Gulf countries. Sending a tough message to Tehran shortly after pragmatist Hassan Rouhani was re-elected president, Trump urged Arab leaders to unite to defeat militants, and said Iran had for decades "fueled the fires of sectarian conflict and terrors." Trump's choice of Saudi Arabia, Iran's bitter regional rival, for his first official foreign visit reflects the deep antagonism of his administration towards Iran.

Iran, which has been accused of exposing sectarian fault lines in the region, especially in Yemen, Syria and Iraq, tried to soften its rhetoric as Rouhani said there should be greater unity between Shiites and Sunnis and that they had coexisted side by side peacefully for hundreds of years. During the Barack Obama era, Iran enjoyed the opportunity to fill the vacuum in the Middle East after the White House abandoned its traditional allies, like Turkey and Saudi Arabia.

Referring to Iran as "the number one terrorist state," the U.S. president said the Middle Eastern country supplies money and weapons to terrorist groups. The Trump administration hit the ground running, re-imposing sanctions against Iran in its first weeks in office and also instating restrictions against those who are complicit with Tehran.