A joint statement from Van Rompuy and Barroso stated Greece "has taken an important step forward along the necessary path of fiscal consolidation and growth-enhancing structural reform".
"But it has also taken a vital step back - from the very grave scenario of default," they added.
European parliament president and former Polish premier Jerzy Buzek said the landmark vote, in the years to come, "may be seen as a turning point for Greece and the eurozone".
"This was not an easy choice to make and I salute those who voted in favour of this tough reform package," Buzek said.
In a related development, the two biggest groups in the European Parliament, the European People's Party (PP) and the Party of European Socialists (EPS) also praised the Greek Parliament's vote.