Iran’s major cities descended into chaos Saturday as anti-government protesters hurled stones at cops — who fought back with tear gas.

Social media reported that two demonstrators were shot dead by police in the western town of Daoud.

Officials urged people to stay away from “illegal gatherings.’’

But the warning failed to persuade furious Iranians, who had been holding protests since Thursday, the Sunday Times of London reported.

President Trump took to Twitter to show his support for opponents of the government.

“Oppressive regimes cannot endure forever, and the day will come when the Iranian people will face a choice. The world is watching!’’ he wrote at 2:02 p.m.

“The entire world understands that the good people of Iran want change,” he wrote in an earlier tweet, “and, other than the vast military power of the United States, that Iran’s people are what their leaders fear most….”

Outside Teheran University, some 70 protestors and police fought under clouds of tear gas.

Demonstrators at rallies around the country shouted slogans against the country’s president, Hassan Rouhani, whose supporters had hoped he’d be a reformist, as well as Iran’s supreme leader, Ayatollah Khomeini.

Even in the town of Qom, which has close ties to Islamic clerics, a crowd shouted, “We don’t want an Islamic republic!’’ and “Death to Rouhani!’’

Iranian cops busted several demonstrators as protestors demanded they be let go.

Trump tweeted that Tehran should “respect their people’s rights. Including right to express themselves.”

Foreign Ministry spokesman Bahram Qassemi responded, “The Iranian people see no value in the opportunistic claims by American officials and Mr. Trump.”

Meanwhile, thousands of government supporters gathered in Tehran for an annual rally to memorialize the crushing of pro-reform protests in 2009.

Iranians are not only disenchanted with their political leaders. Their discontent also has been fueled by economic issues.

Iran’s economy has improved somewhat since the 2015 nuclear deal, in which the country won an easing of sanctions in exchange for cuts to its nuclear program.

But ordinary citizens have not seen any of the benefits.

Unemployment is at 12.4 percent. For young people, it’s more than 40 percent.

Many educated young Iranians see their only future abroad.

There’s also widespread outrage over rising prices and allegations of corruption, as the economy has been hampered by an 8 percent inflation rate, with food shortages contributing to higher prices.

Many Iranians are also angry at the country’s costly involvement in regional conflicts in Iraq and Syria.

With Wires