The Brazilians went on the rampage as fans gathered to watch the England-Uruguay game, which the South Americans won 2-1. (Agencies)
Initial reports said the Brazilians had thrown Molotov cocktails or flares, but police spokesman Romulo Gabrette Lara said the projectiles were in fact relatively small firecrackers of the kind used at Brazil's traditional June festivals.
"They have powder, they make a big noise, but they don't burn. They were thrown in the direction of the England fans," he said.
"The people who were in the bar ran, there was a commotion, but no one was hurt or hospitalized," he added.
Police said they had confiscated six flares and other fireworks from those arrested, plus a knife and brass knuckles.
"Their plan was to throw some noisemakers and use the fireworks in case there was a confrontation," said Lara.
He said the incident stemmed from a fight between English hooligans and an organized group of Brazilian fans at the 2010 World Cup in South Africa.
"Apparently, (the Brazilians) wanted to provoke a repeat, but the people in the bar weren't hooligans, they were just English fans and families," he said.
The bar is located near the official "fan fest" in the center of the Brazilian business hub, where thousands of people have been gathering to watch the action on a giant screen.
There have been other incidents there since the World Cup opened on June 12.
Police said four people were arrested Tuesday when a group of fans attempted to leap metal barriers outside the fan fest area.
Local media said police used pepper spray to disperse the crowd. Up to 30,000 people can gain access to the fan park, but if numbers exceed that, organizers automatically receive notification not to let more people enter.
England lost their match against Uruguay 2-1 and are facing elimination.
The Brazilians went on the rampage as fans gathered to watch the England-Uruguay game, which the South Americans won 2-1.