Football's governing body raised concerns about transport after the Confederations Cup last June but Blatter said it was time to have faith that the month-long tournament starting in June would be a success.
"South Africa is a tourist country that welcomes 11 million visitors a year so I don't know why there are doubts when it comes to football," he said at a news conference after meeting Spanish Prime Minister Jose Luis Rodriguez Zapatero in Madrid.
"The issue (of transport) will be definitively resolved for the World Cup," he added, speaking in Spanish.
"Let's have confidence in Africa and let's end the doubts and go there together with the best players," he said.
"It's justice for Africa which has given a great deal to international football."
