This is the incredible moment hundreds of Iranian students refuse to step on the American and Israeli flags amid anti-government marches in the country and a warning to its leaders from Donald Trump to 'not kill protesters'.

The clip taken at Shaheed Beheshti University on Sunday shows crowds deliberately avoiding walking over the Stars and Stripes and the Star of David before furiously berating those that do.

Ali Khamenei's regime is said to have painted the flags at the main entrance of the university for students to walk over as a sign of disrespect.

In 2016, Iranian professor Sadegh Zibakalam, who has avoided walking on the flags in the past, said: 'It is a sign of disrespect toward that nation. Placing the flag of a country on the ground and stepping on it is an error, a sign of disrespect toward that nation.'

Thousands had on Saturday gathered in front of the gate of the Amirkabir University of Technology near the former US embassy in Tehran to protest the government and Iran’s Supreme Leader Ayatollah Ali Khamenei for mistakenly downing a civilian passenger plane.

President Trump issued a stark warning to the leaders of Iran Sunday, tweeting: 'To the leaders of Iran - DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching.

'More importantly, the USA is watching. Turn your internet back on and let reporters roam free! Stop the killing of your great Iranian people!'

Iranian students refuse to step on the American and Israeli flags in a video taken Sunday

The clip taken at Shaheed Beheshti University on Sunday shows crowds deliberately avoiding walking over the Stars and Stripes and the Star of David

Ali Khamenei's regime is said to have painted the flags at the main entrance of the university for students to walk over as a sign of disrespect

Really interesting.



Iranian students during anti-govt protests refuse to step on Israeli and American flags printed by the local authorities on the road pic.twitter.com/gFfFho62vT — Ragıp Soylu (@ragipsoylu) January 12, 2020

Trump had earlier sent a message of support to the people of Iran on Saturday evening, saying 'we are inspired by your courage' as thousands of angry demonstrators protested the regime in the streets of Tehran.

'To the brave, long-suffering people of Iran: I've stood with you since the beginning of my Presidency, and my Administration will continue to stand with you. We are following your protests closely, and are inspired by your courage,' Trump tweeted in English and in Farsi.

'The government of Iran must allow human rights groups to monitor and report facts from the ground on the ongoing protests by the Iranian people. There can not be another massacre of peaceful protesters, nor an internet shutdown. The world is watching,' he added.

On the day after the rally at Tehran's Amir Kabir University, tensions appeared to be mounting again on the streets of the capital, with a heavy police presence notably around the iconic Azadi Square south of the center.

Riot police armed with water cannon and batons were seen at Amir Kabir, Sharif and Tehran universities as well as Enqelab Square. Around 50 Basij militiamen brandishing paintball guns, potentially to mark protesters to authorities, were also seen near Amir Kabir.

Officers could be seen massing in Vali-e Asr Square in the city as calls circulated for protests. A large black banner unveiled in the square bore the names of those killed in the plane crash.

The plane crash early on Wednesday killed all 176 people on board, mostly Iranians and Iranian-Canadians.

Iran's top Guards commander briefed parliament on Sunday, a day after the armed forces said the Ukrainian airliner was shot down in error in an admission that sparked an angry demonstration.

After initially blaming a technical failure, authorities finally admitted to accidentally shooting it down in the face of mounting evidence and accusations by western leaders.

People gather for a candlelight vigil to remember the victims of the Ukraine plane crash, at the gate of Amri Kabir University where some of the victims of the crash were former students

Iranians shout slogans against the government after a vigil held for the victims of the airplane of Ukrainian International Airlines that crashed near Imam Khomeini Airport turned into an anti-government protest outside Amirkabir University in Tehran

The plane was shot down as Iran braced for retaliation after firing ballistic missiles at two bases in Iraq housing American forces.

The ballistic missile attack, which caused no casualties, was a response to the killing of General Qassem Soleimani, Iran's top general, in a US airstrike in Baghdad.

Iranians have expressed anger over the downing of the plane and the misleading explanations from senior officials in the wake of the tragedy.

Revolutionary Guard Gen. Qassem Soleimani, the head of Iran's elite Quds Force, was killed in an airstrike at Baghdad's international airport

A candlelight ceremony late on Saturday in Tehran turned into a protest, with hundreds of people chanting against the country's leaders — including Supreme Leader Ayatollah Ali Khamenei — and police dispersing them with tear gas.

Police briefly detained the British ambassador to Iran, Rob Macaire, who says he went with the intention of attending the vigil and did not know it would turn into a protest.

'Can confirm I wasn't taking part in any demonstrations!' he tweeted. 'Went to an event advertised as a vigil for victims of #PS752 tragedy. Normal to want to pay respects — some of victims were British. I left after 5 mins, when some started chanting.'

He said he was arrested 30 minutes after leaving the area.

The UK said its envoy was detained 'without grounds or explanation' and in 'flagrant violation of international law'.

'The Iranian government is at a cross-roads moment. It can continue its march towards pariah status with all the political and economic isolation that entails, or take steps to de-escalate tensions and engage in a diplomatic path forwards,' Foreign Secretary Dominic Raab said in a statement.

Iran's deputy foreign minister Abbas Araghchi later tweeted that Macaire was arrested 'as an unknown foreigner in an illegal gathering'.

Araghchi said when police informed him that a man was arrested who claimed to be the British ambassador he did not believe them.

But he said that once he spoke toMacaire by phone he realized it was him, and that the ambassador was freed 15 minutes later.

Alaeddin Boroujerdi, a member of Iran's parliamentary committee on national security and foreign policy, nevertheless accused the ambassador of organizing protests and called for his expulsion.

Officials stand near the wreckage after an Ukraine International Airlines Boeing 737-800 carrying 176 people crashed near Imam Khomeini Airport in Tehran, killing everyone on board

One of the engines of the plane lies among the wreckage. The plane was shot down as Iran braced for retaliation after firing ballistic missiles at two bases in Iraq housing American forces

Dozens of hard-liners later gathered outside the British Embassy over the weekend, chanting 'Death to England' and calling for the ambassador to be expelled and for the closure of the embassy. Police stood guard outside the facility.

Iranian media, meanwhile, focused on the admission of responsibility for the crash, with several newspapers calling for those responsible to apologize and resign.

The hardline daily Vatan-e Emrouz bore the front-page headline, 'A sky full of sadness,' while the Hamshahri daily went with 'Shame,' and the IRAN daily said 'Unforgivable.'