He told a rally of supporters in Glasgow that “Nationalism never built a school” and would only serve to set “Scotland against England”.
His words came as First Minister Nicola Sturgeon said that she would be prepared to have her MPs vote down a Labour Budget if Mr Miliband was not prepared to deal with the Nationalists at Westminster. She also accused Mr Miliband of “losing the plot” over the issue.
And former Labour energy minister Brian Wilson last night said Labour’s struggles are partly down to the party “contemplating its own navel” instead of defending its record in government.
Mr Miliband was in Scotland attempting to shore up the party’s floundering vote north of the Border, as polls suggest the SNP could win more than 50 of the country’s 59 seats in next week’s election.
“Nationalism doesn’t understand we are stronger, not weaker, when we look after each other across the whole of our country,” he said.
“Nationalism never built a school. It never lifted people out of poverty. It never created a welfare state that healed the sick and protected our most vulnerable. Nationalism cannot create the jobs we need.”
Labour believes in “the principles of sharing and solidarity”, he added, that underpin the partnerships of four nations in the modern UK. He added: “If we set England against Scotland, if we set any part of our country against another, it does not help working people, it harms working people.
“It undermines the ability to share resources. It drives down wages and conditions in the race to the bottom.”
With less than a week to go until polling day, Labour is facing heavy losses in Scotland, where support for the SNP has been surging since the independence referendum.
While this reduces Labour’s chance of winning a majority at Westminster, Mr Miliband again made clear that he would not do a deal with the SNP after 7 May.
He said: “I know the people of Scotland want a more just society. And with food banks, payday lenders and the neglect of the NHS, Scottish people feel there must be no delay.
“That’s why I have a clear message for the people of Scotland today: Don’t gamble with the SNP when you can guarantee change with Labour.”
Mr Miliband hit back at Ms Sturgeon’s claims that if Labour fails to work with Scottish Nationalists this would see David Cameron win a second term as Prime Minister.
He added that if the SNP wins dozens of seats from Labour in Scotland, this would increase Tory chances of being the largest party.
Mr Miliband vowed: “I will never put the Tories into government. I have spent my entire political career fighting them.
“But the tragedy is that the SNP may very well let the Tories in. That’s what could happen if the Tories are the largest party.”
He continued: “I am also clear there will be no deal, no pact, no coalition, no tie-in with the SNP.
“I don’t say that for tactical reasons – I’m advocating this for principled reasons.
“We cannot do a deal with a party that wants to break up the UK when we want to build it up.”
Mr Miliband was joined at last night’s event by Scottish leader Jim Murphy and shadow Scottish secretary Margaret Curran. It was held in Tollcross leisure centre in Mrs Curran’s Glasgow East constituency, which is a key target seat for the SNP in next week’s vote.
Mr Murphy said: “The Nationalists can buy all the red ties in the world, they can cut and paste our policies into their manifesto, but they will never share our values.”
However, Mr Wilson, who was a key figure in Tony Blair’s government, said Labour has not done enough to defend its record on public spending, particularly after the financial crash.
Writing in today’s Scotsman, he says: “By failing to defend its record between 1997 and 2010, Labour made the most dangerous mistake of politics – it allowed others to write a false narrative which, through repetition, became received wisdom.
“That ground was largely conceded after the last election when Labour reverted to contemplating its own navel, preferring self-flagellation to self-belief.”
Ms Sturgeon turned up the heat on Mr Miliband as she revealed in an interview last night that if Labour won’t deal with the SNP at Westminster, then Nationalists could vote against a Labour Budget, but insisted this would not bring down the government. The First Minister also slammed Mr Miliband’s claim he would rather lose the election than work with the SNP.
“If Ed Miliband is really saying he would rather have a Tory government than work with the SNP for more progressive politics, then it’s final proof that Labour has lost the plot,” she said.
“It will be the final nail in the coffin of Scottish Labour, and I suspect Labour in other parts of the UK, and it makes it all the more important that we have a big team of SNP MPs because we will need them to protect Scotland from the Tories, because clearly Ed Miliband is not prepared to do it.”
She added: “I think people across Scotland, and I suspect across other parts of the UK, will be appalled.
“If Ed Miliband is really saying that if there is an anti-Tory majority in the House of Commons and an opportunity to get the Tories out, he would stand back and watch David Cameron go back into Downing Street rather than work with the SNP, then people in Scotland will never, ever forgive Labour if that turns out to be the case, and I suspect people in other parts of the UK won’t forgive them either.
“I think Ed Miliband is saying these things because he’s being bullied and bossed around by the Tories on this.”
But Ms Sturgeon’s revelation that the party could bring the Budget of a Labour government down came under fire from Kezia Dugdale, Labour’s deputy leader in Scotland.
Ms Dugdale said: “Many people who have trusted Nicola Sturgeon will be shocked to hear her say she will vote down a Labour Budget. A Budget which will bring in measures such as the mansion tax and the bankers’ bonus tax.
“This shows that the people of Scotland should not gamble with the SNP.”