The Rossiiskaya Gazeta daily said the lawsuits were filed against Madonna, concert organisers PMI company and the concert hall, said Alexander Pochuyev, lawyer for the plaintiffs.
Nine people filed lawsuits demanding compensation for 'moral damages' stemming from 'the open promotion of homosexuality' during her Aug 9 concert in Russia's second largest city.
A group of activists from St. Petersburg-based civil group Parental Control asked police to investigate the concert, claiming that children as young as 12 were in attendance. They accused the singer of violating a local law prohibiting the promotion of homosexuality among minors.
During her show at St. Peterburg's largest concert hall, which was attended by 25,000 people, Madonna complained about "growing intolerance" in the world and called for solidarity with gays and lesbians.
She had pink arm-bands distributed in the audience and asked her fans to raise their hands in a show of support for homosexuals.
Madonna also spoke out in support of all-female group Pussy Riot. Three members of the band were sentenced to two years in jail over a February protest in Moscow's largest cathedral against the Orthodox Church's support for Vladimir Putin ahead of the presidential polls.
St. Petersburg's controversial law came into effect in March and has been strongly criticised by rights groups.