At least nine people were killed when Sonko’s supporters clashed with police in several cities on Thursday.
Sonko was not in court when he was given a two-year jail term for immoral behaviour, but cleared of rape charges.
The justice minister said he could be arrested at any time – and police are surrounding his house in the capital.
His supporters fear the conviction could prevent the 48-year-old politician from contesting next year’s presidential election.
Hundreds of officers are blocking his supporters from reaching his home in Dakar – and even his lawyers have been unable to visit him.
When the court handed down its verdict on Thursday, Sonko’s Pastef party called on people to “take to the streets”.
Interior Minister Antoine Félix Diome said the government had imposed restrictions on social media to stop the “dissemination of hate and subversive messages”.
People are upset about the move, which is affecting popular apps like Facebook, Instagram, Messenger, Telegram, TikTok, WhatsApp and YouTube.
They can be accessed using a virtual private network (VPN), but not everyone is aware about such software and how it works.
Several districts of the capital saw clashes – some of the worst confrontations were at the university campus in the city centre where police fired tear gas as vehicles burned and black smoke billowed over the area.
Many businesses closed – and some remained shut on Friday.
There was also violence in the southern city of Ziguinchor, where Sonko is mayor.
Sonko is very popular among unemployed youth and has undergone a meteoric political rise in the last few years.
After his dismissal as a tax inspector in 2016, he was elected to parliament and became mayor of Ziguinchor.
The government has rejected accusations that this case against the opposition leader, as well as others he has faced, were politically motivated.
He was accused of sexually assaulting and threatening a massage therapist at a beauty salon in 2021, which he denied.
Adding to the political tension is the belief that President Macky Sall plans to stay in office for an unconstitutional third term, though he has made no mention of such intentions.
