The decision is the result of anti-Semitic chants sung by some fans during last month's derby against AS Roma.
The penalty will be imposed on the area of the ground that Lazio's hardcore 'ultras' fans occupy if the offence is repeated over the next 12 months.
Therefore, Saturday's home match against Juventus in Serie A will not be affected.
In the chant, the fans sung that Roma supporters "pray in the synagogue".
The judge also fined Roma 8 thousand euros for racist chants directed at Sampdoria's Serbian coach Dejan Stankovic on Sunday, when they called him a "gypsy".
The fine was lowered because Roma coach Jose Mourinho intervened to try to stop the chants.
ANSA