Russian Prime Minister Vladimir Putin on Thursday accused the United States of stirring up controversy over Russia's polls and warned those protesting the result they would be punished if they broke the law.
After three days of protests against election results the opposition says were rigged, Putin said the authorities should enter into dialogue with the opposition.
But he accused some of its leaders of acting selfishly.
"If somebody breaks the law then the security forces must implement the law with full legal means," Putin said.
Russia's opposition has vowed to stage a mass protest in Moscow at the weekend to contest the results of elections, despite the arrest of around 1,000 people in previous demonstrations.
Putin lashed out at United States secretary of state Hillary Clinton, who he said had criticised Sunday's elections before even reading the reports of international monitors.
The US criticism "had set the tone for some people inside the country and given a signal," Putin said. "They heard the signal and with the support of the US State Department started active work.
Putin also said there should be dialogue between the regime and the opposition.
Around 1,000 people have been arrested in three days of demonstrations protesting what they say was mass fraud in Sunday's polls.
The election was won by Putin's ruling party, though with a sharply reduced majority and less than half the vote.