(Adds injuries, detentions)
RIO DE JANEIRO, July 13 (Reuters) - Police in Rio de Janeiro used tear gas to disperse a small group of protesters who tried to push past a blockade before the World Cup final on Sunday, leaving at least four people injured.
The confrontation took place in the Seans Peña plaza, two kilometers (1.4 miles) from the Maracana stadium about an hour before the start of Argentina-Germany final. Fans inside the stadium seemed unaware of the protest.
A military police spokeswoman said four people had been detained and four were injured, two protesters and two police, when the demonstrators tried to make their way towards Maracana.
Protests across Brazil have petered out since the month-long soccer tournament started on June 12, but authorities are trying to preempt violence during the final now that Brazil is out of the tournament and online videos have encouraged violent fringe groups to return to the street.
Police in Rio on Saturday detained 19 people with a history of committing vandalism during protests, earning sharp condemnation from human rights groups that said the detentions were unwarranted.
Images showed protesters carrying banners that read "Protesting is not a crime" and "FIFA Go Home" on the last day of the month-long tournament.
A police crackdown against students a year ago was considered largely responsible for setting off a protest movement that brought more than a million people into the streets to air grievances over corruption and rising prices and to contrast the high cost of the tournament with the poor state of public services.
About 26,000 security forces were on duty during the final match attended by several presidents, while 1,500 private security guards were inside Maracana.
The mood was celebratory in much of the host nation as Brazilians cheered Germany's victory over arch rival Argentina. (Writing by Caroline Stauffer; Editing by Sandra Maler)