Videos on social media in recent days have shown people marching in the streets of several cities, chanting radical slogans. Iran's currency has dropped to a record low ahead of the imposition of renewed American sanctions, with many fearing prolonged economic suffering or possible civil unrest.
Iran will ease foreign exchange rules, state TV reported on Sunday, in a bid to halt a collapse of the rial currency, which has lost half its value since April due to fears about the return of USA sanctions.
The United States says it is about to re-impose sanctions on Iran after President Donald Trump pulled out of the 2015 Nuclear deal in May.
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 threats to shut down the strategic Strait of Hormuz, a vital shipping lane for worldwide oil supplies.
There have been ongoing rumours that Trump and Rouhani could meet in NY later this month, where they are both attending the UN General Assembly - though Rouhani reportedly rejected USA overtures for a meeting at last year's event.
Israel supported the imminent resumption of US sanctions.
A state body led by President Hassan Rouhani and including the heads of the judiciary and parliament on Sunday partially lifted a ban on the sale of foreign currency at floating rates, allowing exchange bureaux to sell at unofficial market rates for purposes such as overseas travel.
However, a Saudi official told Arab News that the decision signals "no change in position whatsoever" with regards to the relationship with Iran.
Last month, United States officials familiar with the matter said the Trump administration had launched a communications campaign to foment unrest and put pressure on Iran to end its nuclear programme and its support of armed groups.
At least for now, the USA is fixated on bringing as much diplomatic and economic pressure to Iran as possible - though it is not clear where things are headed or if there is an increased risk of conflict. "They've got to - well, they've got to behave like a normal country".
Iran Air announced it would take delivery of five ATR aircraft from the French-Italian firm on Sunday, sneaking under the wire before the sanctions return.
Increased US hostility has also driven a run on Iran's currency, which has lost around two-thirds of its value in six months.
It is not yet clear how all this will affect ordinary Iranians, but a European diplomat in Tehran who monitors the economy said prices of basic foods were already creeping up. The first round of financial sanctions should return Monday.