European Commission President Ursula von der Leyen on Saturday called for the release of all imprisoned protesters in Iran and for full restoration of internet access in the country.

"Tehran's streets, and cities around the world, echo with the footsteps of Iranian women and men demanding freedom. Freedom to speak, to gather, to travel and above all to live freely," von der Leyen wrote on social media.

"Europe stands fully behind them. We unequivocally condemn the violent repression of these legitimate demonstrations. Those responsible will be remembered on the wrong side of history.

"We call for the immediate release of all imprisoned demonstrators. We call for the restoration of full internet access. And we call, at last, for fundamental rights to be respected."

Iran has been shaken by nearly two weeks of mass demonstrations triggered by a crippling economic crisis. Activists say dozens of protesters have died in a harsh crackdown by security forces.

The authorities have maintained a nationwide internet blackout since Thursday, according to monitoring groups, with telephone lines also cut.