"We surely regret and resent when outside involvement in the internal events in Kiev (Ukraine's capital) becomes obvious," a newspaper Thursday quoted Kremlin spokesman Dmitry Peskov as saying.
Moscow could not understand why foreign diplomats in Kiev had advised Ukrainian authorities how to act and deal with opposition riots, he said, calling that behaviour "unimaginable" and "causing rage" in Moscow, reported Xinhua.
"Russia and Ukraine are brotherly nations and Moscow watches events in Kiev with great attention and worry," the official said, adding that Russia has advised Ukrainian authorities on how to normalise the situation.
Moscow believed it was unacceptable for other nations to interfere in its neighbour's affairs, he said.
All Kiev's decisions were sovereign and made in the frame of democratic procedures, so any use of political tactics by outsiders was unacceptable, Peskov said.
The State Duma, or lower house of the Russian parliament Wednesday urged Western political circles to stop meddling in the internal affairs of Ukraine in violation of international law.
Mass protests in Ukraine began Nov 21 last year following a government decision to put on hold an association agreement with the European Union and opt for closer relations with Russia.
Since last weekend, more than 300 people have been injured during the unrest in central Kiev.