Iranian Foreign Minister Mohammad Javad Zarif on Saturday denounced renewed U.S. sanctions against its central bank as an attempt to deny ordinary Iranians access to food and medicine, and said the move was a sign of U.S. desperation. 

The United States on Friday imposed a new round of sanctions on Iran, some aimed at its central bank and sovereign wealth fund, following attacks on oil facilities in Saudi Arabia that Riyadh and U.S. officials have blamed on Iran. 

The U.S. Treasury announced in a statement that it has blacklisted Iran's central bank and its national development fund, which it claimed have been used to "move Iran's foreign currency reserves for terrorist proxies." Earlier, U.S. Treasury Secretary Steven Mnuchin said the central bank was Tehran's last source of funds. 

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Iran denies involvement in the attacks, which initially halved oil output from Saudi Arabia. Responsibility was claimed by Yemen's Houthi movement, an Iranian-aligned group fighting a Saudi-led alliance in Yemen's civil war. 

"This is a sign of U.S. desperation ... When they repeatedly sanction the same institution, this means their attempt at bringing the Iranian nation to its knees under 'maximum pressure' has failed," Zarif told reporters in remarks shown on state television. 

"But this is dangerous and unacceptable as an attempt at blocking ... the Iranian people's access to food and medicine," Zarif said, speaking after arriving in New York for the annual U.N. General Assembly next week. 

Meanwhile, there were reports on social media that a number of Iranian servers and websites – including those of some petrochemical firms – were under a cyber-attack. There was no immediate official comment, and the websites of the main state oil company NIOC (National Iranian Oil Company) appeared to be functioning normally. Residents said their internet access was not affected. 

NetBlocks, an organization that monitors internet connectivity, said its data showed "intermittent disruptions" to some internet services in Iran starting from Friday evening. 

But the group said the impact was limited, affecting only specific providers, and the cause was unclear. "Data are consistent with a cyber-attack or unplanned technical incident on affected networks as opposed to a purposeful withdrawal or shutdown incident," it said in a tweet. 

The fresh sanctions target the Central Bank of Iran, which was already under other U.S. sanctions, the National Development Fund of Iran – the country's sovereign wealth fund – and an Iranian company that U.S. officials say is used to conceal financial transfers for Iranian military purchases. 

Zarif said he would meet on Wednesday with foreign ministers of the remaining signatories to the 2015 nuclear accord, which was agreed with Britain, France, Germany, China and Russia as well as the United States.

However, the U.S. withdrew the accord last year and re-imposed unilateral sanctions on Iran. 

"I hope the U.S. government realizes that they are no longer the only economic superpower in the world and that there are many countries that want to benefit from the Iranian market," Foreign Ministry spokesperson Abbas Mousavi said, according to Iran's state media.