During his state of the nation address yesterday, he warned that the government won’t allow “provocateurs and extremists” to threaten stability.
The opposition said the proposed changes were welcome but insufficient, vowing to keep up pressure for the vote to be rerun and election officials to be punished.
Mr Medvedev said Russia “needs democracy, not chaos” and that the government would strongly resist foreign pressure.
The statement follows massive rallies against fraud in the vote on 4 December, when the main Kremlin party, United Russia, lost a quarter of its seats.
“We won’t allow provocateurs and extremists to drag society into their adventures, and we won’t allow any outside interference into our domestic affairs,” Mr Medvedev said.
He repeated a pledge to return to direct elections of governors and spelled out Vladimir Putin’s promise to ease registration rules for political parties.
He said 500 people representing more than half of Russia’s provinces would be allowed to register a party – a significant simplification of the current procedure that requires a party to have at least 45,000 members.