Trump posted on Twitter two clips of his speech to the UN General Assembly in September in which he took aim at the Iranian regime, which Washington has held out as its top adversary in the Middle East.
"Oppressive regimes cannot endure forever, and the day will come when the Iranian people will face a choice," he tweeted, quoting from the speech.
"The world is watching!"
Trump's posts, his second time addressing the subject in as many days, came as several hundred anti-government demonstrators clashed with police at the University of Tehran in a third straight day of protests.
