Zimbabwe's biggest internet provider blocked services on Friday.
Zimbabwe on Friday blocked most social media as international criticism mounted of a ruthless security crackdown after anti-government protests.
Police and soldiers have been accused of indiscriminately dragging people from their homes and beating them.
Several hundred people have been arrested and doctors say they have treated scores of victims for serious gunshot injuries.
The United Nations human rights office on Friday urged Harare to "stop the crackdown", voicing alarm over the security forces' "excessive use of force" which included reports of them using live ammunition.
And it urged Zimbabwe's government "to find ways of engaging with the population about their legitimate grievances".
Nationwide demonstrations erupted on Monday after President Emmerson Mnangagwa said fuel prices would double in a country which suffers regular shortages of banknotes, fuel, food and medicine.
The internet was entirely blocked until Friday afternoon, when some service was resumed.
Econet, the biggest internet provider, told customers it had been ordered by the government to re-open the internet "except for specified social media applications."
MDC, the main opposition party, accused the government of trying to suppress information about the security operation, in which between five and 16 people have been killed, activists say.
Accusing the government of "wanton violence", the party warned that the authorities were "planning on further gross human rights violations under the cover of the communications blackout".
Mnangagwa, who succeeded ousted authoritarian president Robert Mugabe in 2017, had promised a fresh start for Zimbabwe after decades of repression and economic decline.
But his election victory in July was tainted by accusations of fraud, and hopes for a new chapter were dashed when troops opened fire on protesters in Harare, killing several, even before the results were announced.
The EU on Thursday joined the US and Britain in criticising the authorities' response to the latest protests.
"The escalation of violence in Zimbabwe over recent days has been aggravated by the disproportionate use of force by security personnel," European Commission spokeswoman Maja Kocijancic said in a statement.
"The shutdown of access to the internet should also be reversed."
The US embassy in Harare said it was "alarmed by credible reports that security forces are targeting and beating political activists and labour leaders".
Leading Zimbabwean activist Evan Mawarire was on Friday remanded in custody until January 31 on charges of subverting the government and inciting violence, apparently after backing this week's national strike on social media.
Wearing his trademark Zimbabwe flag around his neck, he appeared pensive in the dock of Harare magistrates court as his supporters murmured their disapproval at the judge's ruling.
Mnangagwa -- Mugabe's former deputy -- has vowed to revive the country's shattered economy by attracting foreign investment, but shortages have recently worsened.
He is on an overseas investment tour that started in Russia and will end with him mixing with world leaders at the Davos summit in Switzerland next week.
The president, 76, told state broadcaster ZBC, that no leader could "have their security (forces) go to sleep when shops are being looted".
Inflation in Zimbabwe has risen to 40 percent - its highest rate since hyperinflation wrecked the economy 10 years ago and the country adopted the US dollar as its currency.
For months, long queues lasting hours or even days have formed outside petrol stations and banks, where both fuel and cash are rationed.
With US dollar notes scarce, Zimbabweans are forced to withdraw "bond notes" - supposedly equal to US dollars but worth far less in reality.
Mugabe, now 94, ruled Zimbabwe for 37 years from independence from Britain until he was ousted in November 2017.
The military, fearing that Mugabe's wife Grace was being lined up to succeed him, seized control and forced him to resign before ushering Mnangagwa to power.