When Iran turned to Europe more than two years ago in order to address the controversy surrounding its civil nuclear program, it created a favorable opportunity. Here was a chance for Europeans to play a more proportionate role in tackling international problems, and forge an alliance for the benefit of the region and the world.
Given the unjust sanctions imposed upon it by the West, Iran had to diversify its sources of energy- a need that was in fact recognized long before the 1979 revolution. However, the West questions Iran’s right to have civil nuclear technologies. According to a recent BP estimate, Iran will be an oil importer in 2024 if it continues to consume oil at current rates [1]. It was on this basis that Iran and three major European countries agreed to work together: On the one hand Iran would assure that its program would be exclusively aimed at civilian purposes and the European Union should help it in this regard.
Talks were making progress when the United States decided to pressure the European Union. Europe countered with a proposal and demanded that Iran should relinquish all of its nuclear activities. In view of this attitude, Iran resumed its uranium enrichment program. As a result of this, the European Union played into the hands of the United States and tried to convince the International Atomic Energy Agency (IAEA) of the need to adopt sanctions. Iran, of course, could not accept this because its purpose is legal and falls within its rights under the Non-Proliferation Treaty. Europe’s opportunity is fading away.

Source
The Guardian (United Kingdom)

This is solely the work of US prejudice”, by Seyed Mohammad Hossein Adeli, The Guardian, September 8, 2005.

[1] N. of the R. Knowing that Iran has the second largest oil reserves of the world.