Vandals defaced one of the country's few monuments to President Boris Yeltsin, covering it with blue paint and chipping the letters of his name on the pedestal, police said.
The monument, a tall stone slab with a carved relief of a stern-faced Yeltsin, was unveiled in Yekaterinburg 18 months ago by then-President Dmitry Medvedev.
State television showed workers hosing the paint off the monument from a cherry picker after the predawn attack on Friday. The culprits face up to three months in jail if found.
"We are deeply outraged by this act of vandalism," Vadim Naumenko of the Boris Yeltsin Presidential Center told RIA-Novosti, urging city authorities to ensure it is not repeated.
"Dialogue and dispute should be conducted in a civilized manner," he said. "Otherwise, we will move from rebellion to rebellion in Russia, from revolution to revolution."
Yeltsin, who grew up in the Sverdlovsk region, of which Yekaterinburg is the capital, gained popularity by challenging the Soviet Union's Communist bosses with calls for faster reform. But he is reviled by many Russians, who accuse him of hastening the Soviet collapse and have dark memories of his rule in the chaotic 1990s.
Yeltsin was elected president of Russia in June 1991, when it was still part of the Soviet Union, and emerged as the undisputed leader of a new Russia after he stared down the tanks of a hard-line Communist coup attempt that August.
Mikhail Gorbachev resigned as president of the Soviet Union in December 1991, sealing its breakup.
Yeltsin was re-elected in 1996 and stepped down in 1999, making Vladimir Putin the acting president, after nine years in power tarnished by economic hardship, war in Chechnya and a decline in Moscow's global clout.
Yeltsin, who suffered health problems and bouts of public drunkenness, died in 2007 at the age of 76.