The petrol price will increase by R1.62 a litre from Wednesday, the energy department said..
World football's governing body gave South Africa $100 million to invest in development projects after the 2010 World Cup, but had not previously said it would establish a similar "social fund" after the 2014 tournament to Brazil.
The Confederations Cup, which serves as a World Cup warm-up event, has been marred by protesters denouncing billions of dollars spent to host the World Cup, money some say should be going towards improving public services.
"We have left a legacy [in South Africa], a special fund of $100 million. This fund is controlled by the Football [Association] of [South] Africa, the government of South Africa and Fifa," Blatter said in Rio de Janeiro.
"I am sure an amount like that, or even higher, will be possible to have here ... the aim from Fifa is not to take profit out of the country, but to put into the country."
Blatter said he can "understand this social unrest" that has rocked Brazil while the tournament has been taking place.
The demonstrations took off earlier this month over a 10 cent hike in bus and subway fare in Sao Paulo and morphed into a mass nationwide movement voicing public dissatisfaction with a range of issues such as government corruption, poor education and health care, and spending on the World Cup.
The government is projecting that $13.3billion will be spent on stadiums, airport renovations and other projects for the World Cup, with an estimated $3.5billion spent on the 12 venues.
As violence escalated in the streets near to Confederations Cup matches, with protesters clashing with police, Brazilian President Dilma Rousseff said her government would start to invest in projects the public had been demanding.
"They have promised to change. This is not our problem, this is a political problem, but something will be changed," Blatter said.
"Then the World Cup will have this platform when finally this can be delivered. It's all a question of patience and a question of trust and confidence."
Blatter also expressed "trust and confidence" in how the authorities coped with "some uncomfortable situations we have witnessed" during the Confederations Cup, declining to comment on the police firing tear gas and rubber bullets at some protesters.
Blatter, though, expects football to help unite the nation.
"Hope is one of the elements of football ... we play football nowadays in all perturbed countries in all the world," Blatter said.
"And not only in the perturbed countries where there are many [security] situations, like in Syria or in Afghanistan where we play football, but also [where] there is some social unrest."