Tehran, Jan 1 (IANS): Iranian President Hassan Rouhani has bashed his US counterpart Donald Trump for "sympathising" with anti-government protesters even as Tehran curbed the social media amid intensifying demonstrations over corruption.

In his first public comments since the wave of anti-government protests began on Thursday, The Irnanian leader said people were free to criticise the government but their protests should not lead to violence, the state-run IRNA reported.

The authorties in Iran have now blocked access to Instagram and the popular Telegram messaging app used by activists to organise and publicise the protests.

President Trump has regularly been tweeting his support for protesters in Iran, most recently saying: "The people are finally getting wise as to how their money and wealth is being stolen and squandered on terrorism."

Trump tweeted on Sunday that it looks like the Iranians "will not take it any longer".

But Rouhani hit back saying: "This man in America who is sympathising with our people has forgotten that he called the Iranian nation terrorists a few months ago. This man who is against the Iranian nation to his core has no right to sympathise with Iranians.

President Rouhani's comments came as a security deputy for Tehran's governor said that 200 people had been arrested after protests on Saturday night including 40 "leaders".

A fourth day of demonstrations saw crowds take to the streets to light fires on the streets and shout "death to the dictator" with water cannon used on a crowd in Tehran.

The Iranian President said: "People are absolutely free to criticise the government and protest but their protests should be in such a way as to improve the situation in the country and their life.

"Criticism is different from violence and damaging public properties. Resolving the problems is not easy and would take time. The government and people should help each other to resolve the issues."

The demonstrations were fanned in part by messages sent on the Telegram messaging app, which authorities blocked Sunday along with the photo-sharing app Instagram, which is owned by tech giant Facebook.

Telegram in particular is very popular in Iran, with more than 50 per cent of the country's 80 million population said to be active on the app.

Iran state TV website reported the decision citing an anonymous source who said it was "in line with maintaining peace and security of the citizens."

Also weighing in on the unfolding crisis was Nikki Haley, America's envoy at the UN, who said the country is "being tested by its own citizens".

"We pray that freedom and human rights will carry the day," she said in a statement.

Haley's comments echoed those of US President Donald Trump, who earlier on Sunday said the US was watching closely for human rights violations.

"Big protests in Iran. The people are finally getting wise as to how their money and wealth is being stolen and squandered on terrorism. Looks like they will not take it any longer," Trump tweeted.

Iran has promised to use an "iron fist" to crush dissent, raising fears of widespread bloodshed after two activists were shot dead in the city of Dorud overnight.

The government has confirmed the deaths, but said the men were killed by "foreign agents" and not the security forces.