Washington is set to reimpose sanctions on Iran on Tuesday following President Donald Trump's decision to abandon the 2015 nuclear deal in May.
"Of course, American bullying and political pressures may cause some disruption, but the fact is that in the current world, America is isolated," Foreign Minister Mohammad Javad Zarif told reporters, according to the semi-official ISNA news agency.
Washington is set to reimpose sanctions on Iran on Tuesday following President Donald Trump's decision to abandon the 2015 nuclear deal in May -- a move opposed by all other parties to the agreement.
"We deeply regret the re-imposition of sanctions by the US," said EU diplomatic chief Federica Mogherini in a statement jointly signed with the foreign ministers of Britain, France and Germany.
"We are determined to protect European economic operators engaged in legitimate business with Iran," the statement added.
But the renewed hostility has already sparked a run on Iran's currency, which has lost around half its value since Trump's announcement.
And it has added to tensions inside Iran, which has seen days of protests and strikes in multiple towns and cities over water shortages, high prices and wider anger at the political system.
Severe reporting restrictions have made it impossible to verify the swirl of claims coming through social media, but journalists did confirm a heavy build-up of riot police on Sunday night in the town of Karaj, just west of Tehran, that has been a focal point of unrest, and said mobile internet had been cut in the area.
Rouhani is due to give a televised address to the nation at 21:40 pm (1710 GMT) on Monday to outline plans for tackling the currency decline and impact of sanctions.
His government eased foreign exchange rules on Sunday, allowing unlimited tax-free currency and gold imports, and reopening exchange bureaus after a disastrous attempt to fix the value of the rial in April led to widespread black-market corruption.
With senior religious authorities calling for a crackdown on graft, the judiciary said Sunday it had arrested the vice-governor of the central bank in charge of foreign exchange, Ahmad Araghchi, along with a government clerk and four currency brokers.
Sanctions are due to return in two phases on August 7 and November 5 -- with the first targeting Iran's access to US banknotes and key industries including cars and carpets.
The second phase -- blocking Iran's oil sales -- is due to cause more damage, although several countries including China, India and Turkey have indicated they are not willing to entirely cut their Iranian energy purchases.
After months of fierce rhetoric, Trump surprised observers last week when he offered to meet with Rouhani without preconditions.
But Zarif suggested it was hard to imagine negotiating with the man who tore up an agreement on which Iran and world powers had spent the "longest hours in negotiating history".
"Do you think this person (Trump) is a good and suitable person to negotiate with? Or is he just showing off?" he said.
There have been ongoing rumours that Trump and Rouhani could meet in New York later this month, where they are both attending the UN General Assembly -- though Rouhani reportedly rejected US overtures for a meeting at last year's event.
Over the weekend Trump once again floated the idea of meeting, tweeting "I will meet, or not meet, it doesn't matter -- it is up to them!"
But that came less than a fortnight after a bellicose exchange between the two presidents, with Rouhani warning of the "mother of all wars" and Trump responding with a Twitter tirade against Iran's "DEMENTED WORDS OF VIOLENCE".
Trump has stated he wants a new deal with Iran that goes beyond curbing its nuclear programme, and ends what America calls its "malign influence" in the region, including its support to Syrian President Bashar al-Assad and militant groups in Lebanon and the Palestinian Territories.
Iran hawks believe the pressure is already showing results, pointing to a surprising lack of harassment by Iranian naval forces against American warships in the Gulf this year.
If Iran senses "American steel they back down, if they perceive American mush they push forward -- and right now they perceive steel," said Mark Dubowitz, chief executive of Foundation for Defense of Democracies, a Washington think tank that lobbied against the nuclear deal.