Security Minister Owen Ncube said the security action caused "loss of life" without giving figures on the number of dead and wounded.
Protesters turned back drivers and blocked buses from carrying passengers in Zimbabwe's two main cities of Harare and Bulawayo as the main labour federation called for three-day nationwide strike. "Full investigations are underway", said Ncube.
The Zimbabwe Association of Doctors for Human Rights earlier reported that at least 13 people had suffered gunshot wounds during the protests.
He said from midnight on Saturday, petrol prices would rise from $1.24 a litre to $3.31 and diesel from $1.36 a litre to $3.11.
Zimbabwe's economy has been in a slump for more than a decade, with cash shortages, high unemployment and recently a scarcity of staples such as bread and cooking oil.
Residents in Bulawayo said police fired teargas "indiscriminately" in the city centre and some residential areas.
Riot police in trucks patrolled downtown Harare. Several cars were torched.
The government says it is aware that prices have been rising, forcing many people to slide into poverty.
"We have always had cooperation in the field of defence and security with Russian Federation".
Budget airline Fastjet cancelled flights to and from Harare "due to the current unrest affecting travel on the streets of Harare". An AFP journalist saw protesters looting a supermarket in Bulawayo.
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Sarri couldn't hide his disappointment, saying that he would have substituted Jorginho for Fabregas if the Spaniard had not left on Friday.
Countries in the region like South Africa and Zambia have similar fuel costs to Zimbabwe, with South Africa selling petrol at around $1.20 per litre and Zambia selling petrol at $1.71 per litre.
In an effort to find a solution, Mnangagwa announced the price of diesel will increase to $3.11 (local bond notes) per litre from US$1.24 (local bond notes), while petrol has gone up to $3.31 (local bond notes) per litre from $1.31 (local bond notes) per litre.
She said food prices had tripled.
"We are suffering. Mnangagwa has failed this country".
The Zimbabwe Trade Union Confederation (ZCTU), for its part, reiterated its call to strike.
Nelson Chamisa, who heads the opposition Movement for Democratic Change (MDC) said the situation was "descending into a humanitarian crisis".
Piers Pigou, an expert in Zimbabwe with the International Crisis Group, trashed the government claims that the protest were being championed by the opposition, saying: "We are now seeing the results of a volatility that has been building for some time and that every one has been very complacent about".
Mnangagwa, who took over from longtime leader Robert Mugabe and won a disputed election last July, also announced a package of measures to help state workers after strikes by doctors and teachers over poor pay.
"On the issue of raising enough foreign currency to introduce the new currency, we are on our way already, give us months, not years", he said.