"Due to the clear, present and imminent danger of breach of peace, the government notifies the public that, for the time being, we will not allow demonstrations within the central business districts of Nairobi, Mombasa and Kisumu," said Security Minister Fred Matiangi.
"The inspector general of police has been advised accordingly."
The outlawing of city centre protests comes as the opposition National Super Alliance (NASA) had promised to step up its demonstrations demanding reforms before the holding of a presidential poll re-run, due on 26 October.
He threatened protest organisers with legal action.
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"It is the responsibility of the organiser that all participants remain peaceful. The organisers shall be held personally liable for any breach of law during the demonstrations," he said.
Opposition leader Raila Odinga said this week that he is withdrawing from the scheduled re-run.
He said that without fundamental reforms to the Independent Electoral and Boundaries Commission (IEBC), the vote would not be free and fair.