Serie A found that around 90 per cent of Lazio's away supporters were involved in racist chanting, yet their punishment has been suspended.
Lazio have avoided immediate punishment for their fans' alleged racist abuse of AC Milan players in last week's Coppa Italia clash.
Milan claimed that monkey chants were directed at midfielders Franck Kessie and Tiemoue Bakayoko in their 1-0 semi-final second-leg home defeat on April 24.
Serie A announced its findings on Monday and suggested that 90 per cent of the travelling Lazio fans were involved in the chanting.
However, the club will not instantly be sanctioned, with the threat of a one-match closure of the Curva Nord section of their Stadio Olimpico stadium suspended for a year.
Lazio will only face this punishment if there is a repeat offence in the next 12 months.
The Rome outfit had moved to distance themselves from any such incidents but also criticised sections of the media for "simplistic" reporting in which they "consider the entire Lazio supporter base jointly responsible for acts carried out by a few".
Kessie and Bakayoko apologised after infuriating Lazio for holding up Francesco Acerbi's shirt to celebrate their 1-0 Serie A victory on April 13.
That incident came after Bakayoko, on loan from Chelsea, appeared to take exception to Acerbi's claims in a pre-match interview that there was "no comparison" between the quality of the teams.