Leaders from EU members backed a measure sponsored by Poland that calls for a single market for electricity and natural gas by 2014.
European Commission President Jose Manuel Barroso said the measure means member states need to work hard to develop a common infrastructure.
"These are key growth and energy reforms that member states are working on and we hope they can also deliver them decisively," he was quoted by the Platts news service as saying.
The measure also calls on energy companies to help consumers reduce demand by 1.5 percent per year through 2020.
The stability of a unified Europe is in question following talks among member states for tighter fiscal discipline. British Prime Minister David Cameron faced strong criticism for rejecting a centralized authority on budget issues and a $260 billion package for the International Monetary Fund to assist debt-burdened countries.