The petrol price will increase by R1.62 a litre from Wednesday, the energy department said..
The 89-year-old Mugabe issued a fiery rallying call to some 20,000 supporters, as he endeavoured to extend his 33-year rule.
"You are our soldiers. You have a battle to fight. Go into the battle well-armed. It's a fight for our lives. It's a battle for survival."
"Go into the battle with the full knowledge that there is a political enemy. This is a do or die struggle," said Mugabe as he launched an attack on the 15-nation Southern African Development Community which had asked him to delay elections.
"Let it be known that we are in SADC voluntarily. If SADC decides to do stupid things, let it be known that we can withdraw from SADC."
The regional bloc has pressed Mugabe to roll back his decision to hold elections on July 31, in order to allow for a series of reforms that would limit the military's role in politics and strip ghost voters from the electoral roll.
Zimbabwe's constitutional court ruled on Thursday that the vote would go ahead.
Mugabe had said the election could be put back two weeks but his main rival, Prime Minister Morgan Tsvangirai, had sought a three-month delay.
As he issued the threat to quit SADC, Mugabe also scolded Lindiwe Zulu, an envoy of South African President Jacob Zuma, who has been the chief mediator on the Zimbabwe crisis.
"Did such a person think that we as a country would take heed of this street-woman's stupid utterances," said Mugabe, without mentioning Zulu by name.
Amid the backdrop of violence the regional and international community pressed Mugabe into an uneasy power-sharing government with Tsvangirai.
The upcoming election will choose a successor to their four-year old administration.
Mugabe's party lost its parliamentary majority to Tsvangirai's party at the last elections for the first time since independence in 1980.
Tsvangirai won the most ballots in the first round of the the 2008 vote, but pulled out of the second round amid violence against his supporters.
Some 200 opposition activists were killed in election-related violence.
Mugabe has vowed his arch-rival should not be allowed to rule the former British colony.
"Those who work with our enemies, our former colonisers the British, never again shall we allow them to taste the leadership of the state," Mugabe said.
He, however, urged supporters to avoid violence this time around.
"Let's kick our opponents with votes. But please no violence. Let's have an election without violence, without intimidation."
Under a new constitution Mugabe could serve another two five-year terms.
He said his party, which is blamed for ruining the country's thriving economy with its seizures of land from whites, would forge ahead schemes to boost housing, health services, food security and create jobs.
"We want to succeed. We need a political life," he said at a rally held at Zimbabwe Grounds, in the capital's Highfield township where he gave his first speech emerging from seven years of a guerrilla warfare against white minority rule in 1979.
But he and his party face an uphill struggle to win over voters, many of whom are disgruntled at the poor state of the economy that has forced millions of Zimbabweans to emigrate to neighbouring countries.
New polls were supposed to have been held 18 months after the formation of the power-sharing government in 2009 but were delayed by frequent disagreements among the parties over electoral reforms.
Political observers have warned that elections without reforms will be doomed.