US President Donald Trump tweeted a message of support for the people of Iran on Saturday in both English and Farsi.
Trump says his administration is "inspired" by the courage ofthe protesters who have taken to 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," he tweeted in both English and 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.
The tweets show Trump's solidarity with the thousands of people who gathered in front of the gate of the Amirkabir University of Technology, near the former US embassy in Tehran, to protest Iran's Supreme Leader Ayatollah Ali Khamenei, for unintentionally downing a civilian passenger plane and killing 176 people.
Iran admitted on Saturday that its Revolutionary Guard Air defense forces mistakenly brought down Ukrainian Airlines Flight 752 shortly after it took off from Tehran on January 8.
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"Armed Forces internal investigation has concluded that regrettably missiles fired due to human error caused the horrific crash of the Ukrainian plane & death of 176 innocent people," President Hassan Rouhani said on Twitter.
"Investigations continue to identify and prosecute this great tragedy and unforgivable mistake," he added.