Medvedev told the World Economic Forum in Davos, Switzerland, that the Kremlin was frustrated with roadblocks to energy developments under consideration by EU leaders.
"On critically important markets, primarily the energy market, unnecessary obstacles to effective work are being erected," he was quoted by Russia's state-run news agency RIA Novosti as saying.
European leaders last year investigated the business practices of Russian energy company Gazprom, a world leader in natural gas, in Eastern Europe.
A contractual dispute between the Ukrainian government and Gazprom in 2009 exposed vulnerabilities in the EU energy sector. Europe gets about 20 percent of its natural gas from Russia, though most of that runs through Ukrainian transit networks.
The so-called EU Third Package for energy markets would cut off producers like Gazprom from transmission networks.
"We ourselves are interested in such changes but unilateral actions lead to other consequences and this is unacceptable for Russia," Medvedev said.