Speaking to reporters from the northeastern state of Alagoas, Rousseff said federal law enforcement officers will be used to beef up local police forces in the 12 cities where World Cup games will be played and that the equivalent of $791 million is being spent to this end.
"And if necessary we will also mobilize the armed forces," she added.
"We will guarantee the security of fans, tourists, teams and the chiefs-of-state that will visit us. I am certain we will host the cup of cups," Rousseff said.
The fears of violence during the World Cup stem from last June's protests that erupted around Brazil against bus fare hikes, corruption, poor public services and the billions of dollars being spent on the World Cup and 2016 Rio de Janeiro Olympics.
Last month, the Rio de Janeiro state government announced that a special police battalion had been created to help control violent demonstrations expected during the World Cup and other large sporting and cultural events held in public venues.
The battalion is composed of about 500 specially trained officers recruited from police units statewide.
Rio's Maracana stadium will host seven World Cup games including the July 13 final.
Earlier Wednesday, FIFA Secretary General Jerome Valcke insisted that cities hosting World Cup games must pay for the Fan Fests that allow fans without tickets to watch matches on large screens in public areas.
Speaking in the city of Florianopolis, Valcke said some cities were concerned about the Fan Fests as they could be an easy target for anti-government demonstrators who are against the billions being spent on the World Cup. He added that FIFA was open to changes because of security concerns.
"We are always discussing. We are open. Following what happened last June with the demonstrations, and for security issues, we are always open to move from the first location we have agreed on to the next location which is safer," he said. "We agreed that in Brasilia the Fan Fest will not be located where we were thinking but in a new place."