Iran's president on Monday urged Iranians to put a curse on the United States, Israel and Saudi Arabia, reiterating his long-standing charge that the US and its allies are responsible for the country's ailing economy.

President Hassan Rouhani's remarks were meant to deflect criticism of his administration's performance amid a spiralling economy after President Donald Trump last year pulled America out of the nuclear deal and re-imposed sanctions on Tehran, targeting Iran's vital oil sector.

"Put all your curses on those who created the current situation," Rouhani urged Iranians, adding that "the United States, the Zionists" and Saudi Arabia were to blame.

He didn't say what kind of curses the Iranians should invoke.

The US plan, Rouhani claimed, was to "dominate" the Iranian nation, something Washington will not achieve.

On Sunday, the same day he inaugurated a new phase in the development of a massive natural gas field, Rouhani said Iran's inflation is "above 20 per cent" and that this country of 80 million people has more than 3 million unemployed.

He promised to increase wages in both the government and the private sector, and raise pensions.

The crisis that is gripping Iran has hurt ordinary Iranians and emboldened Rouhani's critics to openly call for his ouster.

Rouhani, who first came to power in 2013, was re-elected for a second term in 2017, promising to improve the economy and foster more open relations with the world.