The Foreign Secretary has been consistently tipped despite his refusal to commit himself to become the new High Representative created by the Lisbon Treaty.
European leaders will gather next week to make that appointment and name the European Council's first president.
But Mr Miliband repeated his rejection of the post and said: "I came into politics to serve the British people in Britain."
Speaking after talks with German foreign minister Guido Westerwelle, he added: "I am committed to Britain and I am committed to the Labour Government.
"There will be a general election in this country within a matter of months. It is a massive choice for the country.
"And so when the choice came to me about whether to stay in Britain or leave Britain, there was only one answer: it is to stay and fight for the kind of Britain I believe in."
Mr Miliband added: "That's very, very clear in my mind and I don't think there should be room for any doubt in yours."
Business Secretary Lord Mandelson - a former EU commissioner - also insisted that he was not interested in the post of high representative.
"It is not a job I want to do," he told the BBC.
"I want to remain a member of the British Government, serving the British people. I had my spell in Brussels, now I am home for good.
Mr Miliband added: "I am deeply honoured that leading Europeans should have thought I would do a good job as European High Representative. It's a great job and it's very important that Europe has a strong voice on the international stage.
"(But) when I said in Brussels last week that I was proud to be Foreign Secretary in Gordon Brown's Government, I meant it. And when I said I was not a candidate for the post of High Representative, I meant it."
Mr Miliband made clear that he is still hopeful that Tony Blair could secure the job of President of the European Council.
Although Mr Blair is thought to have fallen behind in the race for the presidency in recent weeks, the Foreign Secretary suggested there was still time for him to revive his candidacy ahead of the November 19 summit, telling reporters: "Eight days is a long time in politics."
Mr Miliband also indicated he was concerned that speculation linking him to the High Representative's post might "torpedo" Mr Blair's bid, as EU politics make it impossible for both of the jobs to go to the same country.
On Tuesday, Gordon Brown said Mr Miliband would not take the job.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article