According to a leader of his Right Opposition party, Gogi Topadze, Kacheishvili was hospitalized with a concussion, cuts, and bruises.
The Interior Ministry confirmed Kacheishvili was attacked, but declined to give details.
Kacheishvili is a Right Opposition deputy in the national parliament, which is dominated by supporters of President Mikhail Saakashvili, and is also commercial director of Georgian brewer Kazbegi.
Valeri Gelashvili, a member of the opposition Republican Party, was severely beaten last month by attackers who stopped his car. He claimed he was beaten by members of a department of the Interior Ministry, which is in charge of police.