He said that there had been “a drop in intensity” of the demonstrations, adding that “about 500 arrests” had been made since the start of the protest movement.
He added that the government suspected overseas involvement.
“There is foreign influence and it is the country that is under attack,” he said, declining to elaborate.
Sonko, a 48-year-old former tax inspector, was initially charged with rape but was on Thursday convicted on a lesser charge of morally “corrupting” a young woman and sentenced to two years in prison.
He claims the charges against him were a bid by the government to torpedo his political career ahead of the presidential election next year.
His conviction may take him out of the running for the 2024 poll.
Clashes between Sonko’s supporters and police broke out after the ruling, leading to 15 deaths over two days, according to government figures.
Shops and businesses were ransacked.
The army was deployed to the streets but scuffles erupted on Friday night in parts of the capital, Dakar, and in Ziguinchor.
Diome accused protesters of trying to “destabilise the country.”
“These are irresponsible people.
They called for demonstrations. They called for public buildings to be burned. They called for the collapse of the state,” he stated.
Sonko was tried in absentia.
Also, he has yet to be taken into custody for his jail term, which is predicted to cause further tensions.
He is presumed to be at his Dakar home, where he has was blocked in by security forces since last weekend. He claims he is being “illegally held.”
Sharp-tongued and charismatic, Sonko has drawn a strong following among Senegal’s youth, who love his barbs against a political elite he refers to as the “state mafia.”
He has spoken out against debt, poverty, food insecurity, under-funded health and education systems and corruption.
Sonko, who has two wives, portrays himself as a devout Muslim and defender of traditional values, and has called for harsher penalties for same-sex relations.
Supporters of President Macky Sall, however, see him as a rabble-rouser who has poisoned political discourse and sown instability.
Dakar residents interviewed by AFP said they feared the possible consequences of his arrest.
“I am really scared because we don’t know how this will all end,” said 46-year-old Fatou Ba, a businesswoman in the Dalifort neighbourhood of Dakar.
“If they want peace; they won’t go and fetch Sonko.”
Another Dalifort resident, Matar Thione, 32, said he felt unsafe in his own country.
“If the protests continue, life is going to get even harder,” he said.