"The court has ruled to place Pavel Ustinov under arrest," the press service said, adding added that the man was being charged with assaulting a government employee.
According to the prosecution, Pavel Ustinov dislocated the serviceman's shoulder during a clash at the mass protest in Moscow on Saturday.
Moscow's district courts have already authorized the arrests of more than 100 people for their participation in the protests.
In late July, a number of Russia's pro-opposition candidates organised mass protests and called for acts of civil disobedience after 57 independent candidates for the Moscow legislature were not allowed to run over alleged electoral fraud.
At the first unauthorized rally on 27 July, over 1,000 people were detained. The unauthorized protest rally on 3 August involved about 1,500 people. About 600 protesters were detained.
