MOSCOW — The calls started coming in the afternoon and tied up phones for hours at the headquarters of at least two organizations strongly critical of the Kremlin. “Putin is life; Putin is the light; love Putin and your life will have meaning; Putin will give you happiness; Putin will open your eyes,” a woman’s ethereal voice chanted over and over and over.

The mysterious recording seemed intended to incapacitate the organizations, the liberal Yabloko party and the opposition newspaper Novaya Gazeta, which have been promoting a large protest against the government of Prime Minister Vladimir V. Putin that is planned for Saturday in Moscow.

It was one of several bizarre episodes in a week that has left many here in a state of excited confusion. Anger over parliamentary elections last Sunday has impelled many Russians to shake off years of political apathy and take to the streets.

The authorities have granted permission for a demonstration of up to 30,000 people on Saturday, a decision that by all accounts is unparalleled in Mr. Putin’s 12-year reign. But they are also taking measures meant to discourage attendance.