Lazio were handed the punishment after fans racially abused Juventus players during last Sunday's Super Cup.
"The Federal Court of Justice has rejected Lazio's appeal against the closure of the Curva Nord. The Serie A Sporting Judge ordered the closure of the sector after chants directed at Juventus' black players," the federation said in a statement on its website (www.figc.it).
During Lazio's 4-0 defeat by Juve, fans were warned about racist chanting over the stadium's loudspeaker after abuse was directed at goalscorer Paul Pogba, midfielder Kwadwo Asamoah and Italian defender Angelo Ogbonna.
It was the latest in a string of incidents involving Lazio fans, who have a reputation for extreme right wing politics.
Last season the club was forced to play two home matches behind closed doors in the Europa League after their fans racially insulted Borussia Moenchengladbach players.
There were also violent clashes before their home match against Tottenham Hotspur when home fans engaged in anti-Semitic abuse and fascist salutes.
(Reporting by Terry Daley, editing by Pritha Sarkar)
