The Iranian government has cracked down on protests, like the one shown above, after massive rallies spilled into Tehran's streets following the presidential election. (Associated Press)

More than 700 people defied government orders in Tehran and took to the streets on Thursday in renewed protest over the results of Iran's presidential elections.

The pro-reform demonstrators chanted "death to the dictator" as baton-wielding police attempted to chase them away and eventually fired tear gas to break up the rally, according to eyewitness accounts.

It was the first public protest in Tehran in 11 days and coincided with the anniversary of a 1999 attack by Basij militia on a Tehran University dorm to stop protests in which one student was killed.

Protesters to be 'smashed'

On Thursday morning, Tehran's governor Morteza Tamaddon had warned that any protesters would be "smashed," and the capital city was virtually shut down on government suspicions that a mass rally might be staged.

Protesters gather around a burning waste bin during a demonstration in central Tehran on Thursday. (Reuters)

"If some individuals plan to carry out any anti-security actions by listening to calls by counter-revolutionary networks, they will be smashed under the feet of our aware people," he said, according to the state news agency IRNA.

Supporters of opposition leader Mir Hossein Mousavi have been calling for protesters to rally on Thursday.

Iran's June 12 election outcome, which handed a 2-to-1 victory to President Mahmoud Ahmadinejad, had spurred allegations of vote-rigging and sent tens of thousands of protesters from both sides into the streets last month.

In the crackdown that followed, at least 20 protesters and seven Basijis were killed and at least 1,000 people were arrested. Police said most have since been released, but security forces have continued to round up dozens of activists, journalists and bloggers.

Massive security forces have kept protesters off the streets for nearly two weeks and Supreme Leader Ayatollah Ali Khamenei has declared the election results valid after a partial recount.

Tehran heavily patrolled

Security forces and militia members were at all intersections along Revolution Street on Thursday and patrolled around Tehran University.

Most of the protesters gathered at the university and wore green surgical masks, the colour of Mousavi's movement, according to eyewitness accounts.

Authorities tried to divert Thursday's rally by cutting off mobile phone text messaging for three days, closing down universities and declaring a government holiday that shut down most of Tehran.

Iranian authorities claim the post-election turmoil has been instigated by enemy nations aiming to thwart Ahmadinejad's re-election, and officials say some of those detained have confessed to fomenting unrest. Opposition supporters say the confessions were forced.

With files from The Associated Press