The UN on Friday condemned the Taliban's increasingly violent response to peaceful protests, including using live ammunition that killed several people.
It said journalists were also being targeted who were trying to "simply to their job" after reporters were arrested and beaten covering demonstrations.
"We call on the Taliban to immediately cease the use of force towards, and the arbitrary detention of, those exercising their right to peaceful assembly and the journalists covering the protests," said Ravina Shamdasani, spokeswoman for the United Nations human rights office.
Her office said armed fighters had been using live ammunition and whips to disperse crowds, killing at least four people since mid-August.
The Islamist hardliners who swept into power on August 15 have pledged a more moderate brand of rule than in their notoriously oppressive 1996-2001 reign.
But they have shown clear signs that they will not tolerate opposition.
Earlier this week armed Taliban militants dispersed hundreds of protesters in cities across Afghanistan, including in Herat, where two people were shot dead.
Shamdasani said the rights office had also received credible reports that a man and a boy were shot dead as Taliban gunmen sought to disperse crowds during national flag-raising ceremonies held last month.
"There is an obligation to ensure that any use of force in response to protests is a last resort, strictly necessary and proportionate," she said.
"Firearms must never be used except in response to an imminent threat of death or serious injury."
She also referred to reports that the Taliban beat and detained protesters in Kabul this week, including several women and up to 15 journalists.
On Wednesday, at least five journalists were arrested and two severely beaten for several hours.
"One journalist was reported to have been told, as he was being kicked in the head that you are lucky you have not been beheaded," she said.
"(There is) lots of intimidation of journalists who are trying to simply do their job," she said.
The Taliban moved to snuff out any further civil unrest late Wednesday, saying protests would need prior authorisation from the justice ministry.
The following day, they ordered telecommunications companies to block internet on mobile phone service in some areas of Kabul, Shamdasani said.
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