Mr Miliband has said he was not available to be a candidate
Gordon Brown has said Foreign Secretary David Miliband was "never a candidate" to become EU high representative.
He has been seen as a frontrunner for the foreign affairs job, one of two created by the EU Treaty, even though he had said he was not "available".
The BBC understands Mr Miliband told the European socialists' group he did not want the role and friends said he "sees his future in British politics".
Mr Brown said Tony Blair was the only person being put forward for an EU job.
He told his monthly media conference: "David Miliband was never a candidate for the high representative job.
"Britain has only one candidate for the European Council positions that are being discussed at the moment.
"That candidate is Tony Blair and his candidature is for the presidency of the council. These matters will be sorted out in the next few days."
BBC political editor Nick Robinson said on Monday that Mr Miliband had rejected the lure of high office in Brussels for the uncertainty of life in a Labour government heading for a difficult election.
He said the foreign secretary's friends had told him there was still a small possibility that Mr Brown might choose to stand down before the election and he would be a natural successor.
In the running
Mr Miliband, foreign secretary since 2007, has been touted as a future Labour leader and was urged by some to challenge Mr Brown for the leadership in 2008.
He had responded to speculation he might take the job of EU high representative for foreign affairs by saying he was not "available" to be a candidate.
But speculation continued in several newspapers on Monday that Mr Miliband was still in the running for the EU job, fuelled by his appearance in Germany at celebrations marking 20 years since the fall of the Berlin Wall.
Candidates for high representative must be nominated by the government of one of the EU's 27 member states.
Mr Miliband has been campaigning for former Prime Minister Tony Blair to get the other job created by the Lisbon Treaty, that of president of the European Council.
But, with reports that Mr Blair's campaign was struggling, there was a suggestion that Mr Miliband might be in the running for the foreign affairs role instead.
Sweden currently holds the rotating presidency of the EU and is expected to call a special summit within the next few weeks for leaders to decide on a president and high representative.