The debacle in the elections prompt European Union leaders to re-evaluate the EU bloc’s agenda.
European Council President Herman Van Rompuy said leaders of the 28 member states had asked him to launch consultations on future policies.
He was speaking after a meeting in Brussels to discuss big election gains by populist and far-right parties, BBC reported.
Meanwhile, former British prime minister Tony Blair has moved to unite the left against Ukip in his strongest attack yet against Nigel Farage and the eurosceptic party.
Mr Blair said Ukip did “not have all the answers” and should be exposed for having “no actual solutions to the problems of the 21st century”.
Blair, 61, told BBC Radio 4’s Today programme that blaming immigrants for problems is a “backwards and regressive step”.
“You look underneath that UKIP facade and you see something pretty nasty and unpleasant,” he said.
The former PM, who served in Downing Street between 1997 and 2007, said: “We are confronted by what I think are these very reactionary forces. We have to confront them, expose them and take them on… you have got to take on and expose the fact these parties have no actual solutions to the problem of the 21st century.”
The results of the European Parliament election led to calls for an EU rethink by those leaders who suffered defeats.
But despite gains by anti-EU groups, pro-European parties still won most votes overall.
Tuesday’s summit was the first opportunity for leaders of all member states to discuss the way forward after last week’s polls.
A BBC correspondent says reforms could include less regulation and less focus on economic austerity policies, while measures to boost growth and create jobs could address voter discontent.
Mr Van Rompuy said the results of the European elections had shown “a mix of continuity and change” and that the Eurosceptic message from voters was “at the heart” of discussions between leaders.
He said the meeting in Brussels had been a “useful first discussion” and that EU leaders had agreed on putting the economy at the heart of the group’s agenda.
As the Union emerges from the financial crisis it needs a positive agenda of growth,” he said, repeating a common refrain of what is needed to reverse growing anti-EU sentiment.
President Francois Hollande asked Europe to “pay attention” to France after describing his Socialist party’s defeat to the far-right National Front as “painful.”
The National Front – which Germany’s finance minister described as “fascist” – stormed to victory with a preliminary 25% of the vote, pushing Mr Hollande’s Socialists into third place.
National Front President Marine Le Pen said she would use her electoral mandate to “defend France” and fight “crazy measures like votes for immigrants.”
Speaking after EU leaders met in Brussels, Mr Hollande said the National Front victory was “traumatic for France and Europe.”
“France cannot live isolated and frightened. Its destiny is in Europe,” he added.
Mr Van Rompuy also told reporters that he would hold talks with the political groups to be formed in the European Parliament on who will be named to head the next Commission, the EU’s executive arm.
On the latest projections, the centre-right European People’s Party will be the biggest political group and its candidate is former Luxembourg premier Jean-Claude Juncker.
EU leaders have traditionally named the Commission head on their own, but under new rules they now have “to take account” of the European election results.