The former Spanish foreign minister said he was "calm and happy"
The European Union's foreign policy chief, Javier Solana, has said he will not seek another term in office.
"I had a 10-year mandate which I have fulfilled. I do not mean to go any further," he told a Spanish newspaper.
A spokeswoman said it was normal that Mr Solana would step down when his term ended in October, and that he would be "very busy doing other activities".
He had been considered a main contender for the new EU foreign policy role set to be created by the Lisbon Treaty.
Under the treaty, which has yet to be ratified by all 27 member states, the post would combine the jobs of the existing foreign affairs supremo and the external affairs commissioner to give the EU more clout on the world stage.
Irish voters rejected the text just over a year ago, but a second referendum is expected in October. If they reject it again, the treaty could be scuppered.
In an interview with Spain's ABC newspaper on Sunday, Mr Solana said he did not intend to stay on as the EU's High Representative for the Common Foreign and Security Policy, regardless of whether Lisbon was or was not ratified.
"These past 10 years have been very important for me, but also I think for Europe," he said.
"We've achieved extraordinary things. We've positioned Europe with its face and its eyes towards the world. When they appointed me in 1999, nothing like this existed," he added.
The 66-year-old former Nato secretary general and Spanish foreign minister said he was "calm and happy" and would continue working with the same intensity until his mandate ended.
His spokeswoman, Cristina Gallach, confirmed his comments and told the BBC he would be very busy doing other activities in other fields.