The president of the European Commission has denied that regulations from Brussels contributed to the UK's flooding problems.
UK Independence Party (Ukip) leader Nigel Farage has called for a public inquiry amid claims that European Union rules made it harder to dredge rivers.
But Jose Manuel Barroso dismissed the accusations that the EU was to blame for the problems as a "caricature" of the work done in Brussels.
Mr Farage has claimed that the Environment Agency is "so hamstrung by a whole series of European directives and we are putting the interests of beetles and voles and birdlife before that of farmers and people".
In a speech at the London School of Economics, Mr Barroso defended the work of the EU and insisted that the UK was "better off" as a member.
In an attack on Eurosceptics, he said despite the effectiveness of the response to the eurozone crisis, "i t is perhaps surprising to see the persistence of some of the doomsayers within Europe".
He continued: "They have updated their tune, of course: the argument is now that Europe lacks the capacity to deliver growth and jobs and faces a lost decade.
"And all too often, instead of looking at the things that need to change at home, it seems much easier to point to 'Brussels' as the ball and chain that is dragging down Europe's growth potential.
"We still see the temptation to Europeanise failure and nationalise successes.
"By the way, that is not the worst we are accused of - just last week Brussels was blamed for the devastating floods here in the south of England. We have also been accused of the death of poor Marius the giraffe in Denmark.
"It's an interesting caricature. But it is just that - a caricature.
"Of course, neither the floods nor the giraffe have anything to do with European regulations or responsibilities at all."
But he acknowledged that immigration within the EU might have put "unintended strains" on local communities.
The lifting of restrictions on the movement of Romanian and Bulgarian citizens at the start of the year has fuelled concern in the UK about EU immigration.
Mr Barroso said: "I am very much aware that free movement may put unintended strains on local communities and services and in some cases there has been abuse. There is a lot that national governments can do to tackle abuses.
"European rules include firm measures to tackle fraud. The European Commission is eager to help."
But he stressed that the commission's members "remain absolutely firm on the principle of free movement".
Mr Cameron's plan is to renegotiate the UK's relationship with Brussels before putting it to an in/out referendum if he is prime minister after the 2015 election.
Mr Barroso said: "I know there are several perspectives on Europe. But I believe the right thing to do is not to turn away but to engage and see what together we can do to make it better. If you don't like Europe as it is: improve it."
Although there is scope for flexibility in the EU, "that does not mean we should move to a Europe a la carte, nor would it be right to put into question our shared values and principles".
"But it is clear that some countries are going to go further, quicker, than others, " he said.
"That is something that I think can - if the political will is there - be accommodated in the same way as diversity in areas such as justice and home affairs and defence has been an integral and workable part of European life for decades now."
He said it is a "paradox" that the UK, a global trading nation, is divided on the issue of the EU.
"The European Union would not have become what it is today if it weren't for British politicians and entrepreneurs, British thinkers and British ideas. Without the UK, Europe would be less reform-driven, less open, and less international. Less effective as a tool for managing and benefiting from globalisation.
"For a country so open to the world, it's a paradox that the UK remains so torn on Europe."
He added: "When it comes to the British question, in the end the British people can judge for themselves. But my very personal, very strong conviction is that the EU is better off with the UK, and the UK is better off in the European Union."
Ukip international trade spokesman William Dartmouth MEP said: "The EU is not responsible for the rain. However, the EU by its ill-thought out heavy-handed regulations, i.e. its water and habitat directives, is heavily implicated in exacerbating flooding in the UK.
"EU directives have tied the hands of the UK's Environment Agency from dredging rivers and instead puts the emphasis on wildlife proliferation rather than flood prevention.
"It is clear that EU puts the habitat of voles and molluscs before the homes and property of the British people."