The Lib Dem leader said the Tories would have to cut 10,000 police officers, 28,000 carers and 25,000 military personnel to pay for the tax cuts promised by George Osborne.
He said the poorest would "bear the heaviest burden".
David Cameron has accused Mr Clegg of "running away from his record".
The Lib Dems have announced that they want to raise the income tax threshold to £12,500 by 2020, which would be funded partly by using the proceeds of measures to clamp down on tax avoidance and evasion.
Mr Clegg said the Tory plans to raise the income tax personal allowance to £12,500, and also increase the 40p rate threshold to £50,000 by 2020 would cost more than £7bn.
At a press conference at the National Liberal Club in London, Mr Clegg said: "To find that money they will have to do what Tories do best - cut.
"Gone are the days of compassionate conservatism. Now they promise to cut and cut and cut. Not because they have to, but because they want to.
"As George Osborne has said, the Conservatives will cut much deeper than is necessary to balance the books and make the poorest bear the heaviest burden.
"But at the same time they are promising tax giveaways for the wealthy, all of which must be paid for by yet more cuts to public spending.
"In the firing line are parents and police officers, soldiers and social workers."
This issue includes the wider economy and deficit reduction but also employment and the role of business.
Policy guide: Where the parties stand
But in an article in The Daily Telegraph Mr Cameron told the newspaper that Mr Clegg's attacks on him will fail, he said: "I don't think it works because you can't run on your record and run away from your record at the same time."
Mr Clegg also went on to criticise Labour and said Ed Miliband's plans for the deficit would mean an extra £134 from every taxpayer being spent on debt interest payments.
"If the Conservatives will cut too much, Labour will borrow too much.
"Labour will borrow £70bn more than we will - meaning an extra £4bn just to pay the interest on our debt," he said.
His sentiments were echoed by the Chief Secretary to the Treasury Danny Alexander who said the "common thread" running through the Lib Dem approach to tax was fairness.
He said: "Fairness means that everyone should pay their taxes, zero tolerance of evasion and aggressive avoidance. Fairness means that as we finish the job of balancing the books, we should ask those who have the most to contribute to most."
But in response to Mr Clegg's claims Chris Leslie, Labour's shadow chief secretary to the Treasury, said nobody could trust the Lib Dems.
He said: "They broke their promise not to raise VAT on families and pensioners and backed the Tory tax cut for millionaires.
"For all their claims, the independent Institute for Fiscal Studies says families have lost £1,100 a year on average when all this government's changes are taken into account - including the changes to the personal allowance. Like the Tories, the Lib Dems give with one hand but take much more with the other hand.
"Labour's plan will back working people with fully funded tax cuts and reverse the Tory and Lib Dem tax giveaway for millionaires to balance the books in a fair way."
Meanwhile, in an interview with The Economist, Nick Clegg has said that many of the voters who have stopped supporting his party "want to be entirely bereft of any responsibility".
He told the publication: "There is clearly a section of the support we had in 2010 that was virulently anti-Conservative.
"They're the ones who still scream and shout blue murder and have done so without pause for breath for half a decade.
"And they're loud and they're noisy and they're angry. And that was a significant chunk of support that basically wanted to be associated with any party that didn't have the remotest sniff of power.
"There just is a constituency out there that wants to be entirely bereft of any responsibility."
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Nick Clegg has attacked the Conservatives' plans for the economy as he stepped up his attack on his coalition partners since 2010.