EU's foreign policy chief Josep Borrell said Sunday that Iran's crackdown on protests is "unjustifiable" and "unacceptable."
In a statement on behalf of the EU, Borrell said: "For the European Union and its member states, the widespread and disproportionate use of force against nonviolent protestors is unjustifiable and unacceptable".
A wave of protests has rocked Iran since the death of 22-year-old Kurdish woman Mahsa Amini in the custody of Iran's morality police.
Amini was arrested on September 13, accused of having breached rules that mandate tightly fitted hijab head coverings as well as ripped jeans and brightly colored clothes.
At least 41 people have died, mostly protesters but including members of Iran's security forces, according to an official toll, although human rights groups say the real figure is higher.
Moves "to severely restrict internet access by the relevant Iranian authorities and to block instant messaging platforms is a further cause for concern, as it blatantly violates freedom of expression", said Borrell.
Hundreds of demonstrators, reformist activists and journalists have been arrested amid the mostly night-time demonstrations that have spread to scores of cities since unrest first broke out after Amini's death on September 16.
Security forces have fired live rounds and bird shots, rights groups charge, while protesters have hurled rocks, torched police cars, set ablaze state buildings, and shouted "death to the dictator".
The world has learnt of the violence largely through shaky mobile phone footage posted on social media, even as authorities have throttled internet access.