President Hassan Rouhani on Tuesday vowed to overcome US sanctions and promised to defeat "anti-Iranian" officials in the White House, calling for a united front amid a deteriorating economy.
It was the first time he had been summoned by parliament in his five years in power, and MPs demanded answers on unemployment, rising prices and the sharp depreciation of the rial, which has lost more than half of its value since April.
The speech in Tehran, broadcast on state television, followed the enforced sacking of Mr Rouhani's labour and economy ministers. But aimed at shoring up his position, the comments did not have the desired affect among the assembled politicians who rejected the president's explanations, appearing to weaken him further.
Mr Rouhani's moderate faction is under pressure from hardline anti-Western factions in Tehran.
Iran's currency has plunged following America's recent re-imposition of nuclear-related sanctions, which has led several major foreign companies to exit the country.
Unemployment is also rising but Mr Rouhani laid the blame for the current woes at President Donald Trump's door, following the US withdrawal from the nuclear deal in May.
"The economic problems are critical but more important than that is that many people have lost their faith in the future of the Islamic Republic and are in doubt about its power," he said, while answering politicians' questions.
"We are not afraid of America or the economic problems," he said. "We will overcome the troubles. We will not allow a bunch of anti-Iranians who have gathered in the White House to conspire against us."
The Iranian president also mentioned a third way to deal with the crisis, other than abandoning or keeping the nuclear deal, but did not elaborate beyond saying he had mentioned it to French President Emmanuel Macron in a telephone call on Monday.
"You may talk about employment, foreign currency, recession, smuggling... I think the problem is in people's view of the future," he said.
"If the people see we are united, they will realise the problems will be resolved."
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Defending his cabinet's performance, Mr Rouhani said the economic troubles only began when Washington reimposed sanctions on Tehran, but many legislators did not find that answer satisfying according to vote results at the end of the session reported by Tasnim news agency.
Lawmakers voted against four out of five of Mr Rouhani's responses to questions on the economy, referring the matter to the judiciary for review, although it is unclear whether any action could be taken.
Mr Rouhani, a pragmatist who reduced tension with the West by striking a nuclear deal with world powers in 2015, now faces a backlash from hardliners over Washington’s pullout from the pact.
The agreement had lifted sanctions on Tehran in return for curbs on its nuclear programme.
In Tuesday's speech Mr Rouhani also linked nationwide demonstrations rocked that rocked the country in December to January to Mr Trump decision to exit the accord.
Many countries have withdrawn business from Iran following the re-imposition of sanctions. Subsequently, the action has caused flight routes to be cancelled.
Earlier this month, France told its diplomats and foreign ministry officials to postpone indefinitely all non-essential travel to Iran, citing a foiled bomb plot and a hardening of Tehran's attitude towards the country, according to an internal memo seen by Reuters.
[ British Airways and Air France suspend flights to Tehran ]
The action in parliament is a further sign of how the Trump administration's decision could affect Iran's leadership and its relationship with the outside world.
Iran's rulers have long been divided between a pragmatic faction – headed by Mr Rouhani – that aims for better international relations, and hardliners who are wary of reforms. Mr Trump's decision to abandon the nuclear deal was opposed by traditional US allies in Europe, who argued that he undermined the Iranian president and strengthened the hands of the hardliners in Tehran.
Russia and China, the other two major powers in the nuclear deal, have also criticised America's withdrawal.
While Mr Rouhani, first elected in 2013, and his cabinet run Iran's day-to-day affairs, ultimate authority lies with the Supreme Leader Ayatollah Ali Khamenei, in power since 1989, and now aged 79.
Somewhat bowing to political pressure he recently fired the head of the country's central bank. A deputy central bank governor was arrested by the judiciary on corruption charges in a crackdown that also saw foreign exchange dealers rounded up.
The lawmakers asked Mr Rouhani on Tuesday about five subjects: unemployment, slow economic growth, the fall of the rial, cross-border smuggling, and the lack of access by Iranian banks to global financial services. In votes, the parliament found only his answer about banks satisfactory.