Trump warns Iran against 'massacre' as protests erupt over jetliner downing

US President Donald Trump has said that United States was monitoring Iranian demonstrations closely, warning against any new "massacre" as protests broke out after Tehran mitted to shooting down a passenger plane.

Iran said earlier it unintentionally downed a Ukrainian jetliner outside Tehran, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. firing came shortly after Iran launched missiles at bases in Iraq housing American forces.

President Hassan Rouhani said a military probe into trdy h found "missiles fired due to human error" brought down Boeing 737, calling it an "unforgivable mistake."

At a student protest to pay tribute to crash victims on Saturday, Iranian authorities briefly detained Britain's ambassor, in what British government called a violation of international law. He was later released.

Trump told Iranians -- in tweets in both English and Farsi -- that he stands by m and is monitoring demonstrations.

"To brave, long-suffering people of Iran: I've stood with you since beginning of my Presidency, and my ministration will continue to stand with you," he tweeted.

"re can t be ar massacre of peaceful protesters, r an internet shutdown. world is watching," he ded, apparently referring to an Iranian crackdown on street protests that broke out in vember.

"We are following your protests closely, and are inspired by your cour," he said.

new demonstrations follow an Iranian crackdown on street protests that broke out in vember. Amnesty International has said it left more than 300 people de.

Internet access was reportedly cut off in multiple Iranian provinces ahe of memorials planned a month after protests.

Canian Prime Minister Justin Trudeau has demanded that Iran provide "full clarity" on downing of plane. Ottawa says de included 57 Canians.

Iran's Supreme Leer Ayatollah Ali Khamenei also offered his condolences and ordered armed forces to dress "shortcomings" so that such a disaster does t happen again.

Tehran's ackwledgement came after officials in Iran denied for days Western claims that Ukraine International Airlines plane h been struck by a missile in a catastrophic error.

Kiev-bound jet slammed into a field shortly after taking off from Tehran's Imam Khomeini International Airport on Wednesday.

crash came hours after Tehran launched missiles at bases hosting American forces in Iraq in response to killing of top Iranian general Qasem Soleimani in a US drone strike.

Fears grew of an all-out war between Iran and its arch-enemy United States, but those concerns have subsided after Trump said Tehran appeared to be standing down after targeting US bases.

On Saturday evening, police dispersed students who h converged on Amir Kabir University in Tehran to pay tribute to victims, after some among hundreds gared shouted "destructive" slogans, Fars news ncy said.

British Foreign Secretary Dominic Raab said UK envoy Rob Macaire h been detained.

" arrest of our ambassor in Tehran without grounds or explanation is a flagrant violation of international law," Raab said in a statement. US called on Iran to apologize.

Iran's Tasnim News ncy, which is close to country's conservatives, said envoy h been "provoking rical acts" among students. He was released a few hours later and would be summoned again by Iranian officials on Sunday, it said.

State television reported that students shouted "anti-regime" chants, while Fars reported that posters of Soleimani h been torn down.

aero commander of Iran's Revolutionary Guards accepted full responsibility for Wednesday's accident.

But Brigier General Amirali Hajizeh said missile operator acted independently, targeting 737 after mistaking it for a "cruise missile".

operator failed to obtain approval from his superiors because of disruptions to a communications system, he said.

"He h 10 seconds to decide. He could have decided to strike or t to strike and under such circumstances, he took wrong decision."

Iran h been under mounting international pressure to allow a "credible" investigation after video emerged appearing to show moment airliner was hit.

In foot that New York Times said it h verified, a fast-moving object is seen rising into sky before a bright flash appears. Several seconds later, an explosion is heard.

Iran's military said it h been at highest level of alert after American "threats" and that plane h turned and come close to a "sensitive" military site before it was targeted due to "human error."

Rouhani said Iran h been on alert for possible US attacks after Soleimani's "martyrdom." Rouhani ded he h ordered "all relevant bodies to take all necessary actions (to ensure) compensation" to families of those killed.

majority of passengers on Flight PS752 were Iranians and Canians, including dual nationals, while Ukrainians, Afghans, Britons and Swedes were also aboard.

Rouhani told his Ukrainian counterpart Saturday that "all persons involved in this air disaster will be brought to justice," Ukraine's presidency said.

This is Iran's worst civil aviation disaster since 1988 when US military said it shot down an Iran Air plane over Gulf by mistake, killing all 290 people on board.