Iran’s Supreme Leader Ayatollah Ali Khamenei has accused the US of seeking to undermine Iran’s banks.
In a televised address marking Nowruz – the beginning of the Iranian new year – Mr Khamenei said the US was reneging on the West’s nuclear deal with Iran.
The US imposed sanctions on Iranian companies and individuals in response to ballistic missile tests carried out after international sanctions were lifted as part of the deal.
Iran carried out more tests in March.
Iran says its missiles are for use solely as a conventional deterrent. It says it has ballistic missiles with a range of 2,000km (1,250 miles), which means they would be capable of reaching Israel and US military bases in the Middle East.
Ayatollah Khamenei was speaking in the religious city of Mashdad on the first day of the Iranian new year.
He said the US continued to use its position as a superpower to put pressure on Iran.
“Our banking transactions in all Western countries – and other countries affected by them – face problems.” Mr Khamenei said, blaming the Americans for the problems faced by Iranian banks.
And he complained contenders for the US presidency who had “competed to vilify Iran in their speeches” – which was “a sign of hostility”.
Analysis: Sebastian Usher, BBC Arabic Affairs analyst
A boost to the economy is what Iranians most want from the deal on Tehran’s nuclear programme last year. The lifting of sanctions and the inking of international business deals could see that happen. But the benefits are unlikely to be felt by most Iranians for some time.
For President Hassan Rouhani, the deal was a personal victory. The recent surprise success of moderates at the polls has further bolstered his position.
But the dominant figure remains Ayatollah Khamenei. His New Year’s message was more about resistance and self-reliance than international engagement, underlining the rifts that remain at the heart of Iran’s political elite.