Jose Maria Marin, president of the local organizing committee and the Brazilian football confederation, condemned violent acts by some protesters.
"Any peaceful demonstration must be respected ... it is part of democracy," Marin said. "I will not accept robbery and violence and mobs — nobody wants this kind of thing."
Former Brazil star Ronaldo, a member of Marin's organizing committee, praised protesters for helping to draw pledges from the government to invest in public services.
"I fully support the demonstrations," Ronaldo said. "Brazilians are not against the World Cup or the Confederations Cup. They are against corruption, embezzlement; they are against the way the health system has been managed, the way the education system has been managed.
"It has been wonderful to see Brazilians really rise against this situation and to see most demonstrations have been peaceful and asking for change in Brazil ... we have already seen the results of it because things seem to be moving forward swiftly and the government seems to be responding to the people's calls."
FIFA had been due to reveal ticket prices Monday for the World Cup, but unexpectedly delayed the announcement until July 19.
FIFA Secretary General Jerome Valcke said the delay was for logistical reasons and not to avoid further antagonizing protesting about World Cup costs.
"We want to look at all the issues we have faced at the Confederations Cup," Valcke said. "We want to avoid having 10,000 tickets that are not collected two days prior to the game."
Valcke said there won't be a "big difference" in pricing from the 2010 World Cup in South Africa.