Unknown attackers fired a grenade from a launcher at a restaurant in the city of Nazran in Russia's Ingushetia region overnight.
The explosion provoked a large fire, but no casualties were reported.
The attack occurred hours after a powerful blast shattered a liquor store in the city.
No casualties were reported there either.
Last month, unknown individuals tried to place bombs inside the same liquor store.
Islamic insurgents in Ingushetia and other restive republics of Russia's volatile North Caucasus attack liquor stores and public places selling alcoholic beverages regularly, as Islam prohibits drinking alcohol.
Based on reporting by RIA Novosti and Interfax