Medvedev’s warning on Tuesday comes after OSCE-led observers said the country’s parliamentary election last week were slanted in favor of ruling party United Russia, AFP reported.
“If they watch over the elections, the violations — that is one thing,” RIA Novosti quoted Medvedev as saying. “But the question of what the political systems looks like — that is none of their business.”
Thousands of protesters have taken to the streets of Moscow and Saint Petersburg. Officials say more than 300 have been arrested.
Russia has dispatched troops in central Moscow in a move to ensure the security of its citizens.
US secretary of state Hillary Clinton has accused Russia’s parliamentary vote of being rigged, urging a full investigation. In response, Russia has accused the US and its allies of meddling in Moscow’s internal affairs.
Key Russian lawmaker Konstantin Kosachev has also warned that US criticism of Russia’s vote could further harm bilateral relations.
Putin, 59, formally accepted to stand as the ruling party candidate in the 2012 presidential elections to be held in March.
Putin’s presidency ended in 2008 after two consecutive terms because the Russian constitution prevented him from running a third term.
However, he will be free to run again in 2012. President Dmitry Medvedev is to change the constitution, extending future presidential terms to six years.