The Prime Minister's comments came as he launched the Conservative conference in Manchester with a flurry of policy announcements, including the acceleration of the Help to Buy state-backed mortgage scheme and confirmation that he is not planning post-election tax rises.
Several major lenders announced they have signed up to the second phase of Help to Buy, which will be launched next week - three months ahead of schedule - as part of Tory efforts to show they are tackling the cost of living.
And plans were unveiled at the conference for a transferable tax allowance worth £200 a year to some married couples, as well as an extension of cancer drug funding, a ban on "slap on the wrist" cautions for serious offences and help for armed services personnel to buy homes.
Meanwhile, Mr Cameron denounced Labour leader Ed Miliband's plan for an energy price freeze as "nuts", warning: "Bashing and taxing business is going to cost us jobs, set us back and make sure our economy is weaker."
But Mr Cameron was scathing about the Lib Dems' cherished plans for a tax on wealth, telling BBC1's Andrew Marr Show: "I have never been in favour of this idea. I think it's a bad idea."
Asked if if voters could be confident there would be no mansion tax if he was Prime Minister after the election, Mr Cameron replied: "That's correct. Stamp duty yes, council tax yes, but I think wealth taxes are not sensible for a country if it wants to support wealth creation, wants to reward saving and people who work hard and do the right thing."
The PM defended Help to Buy against warnings from critics, including Lib Dem Business Secretary Vince Cable, that it risks stoking up a property price bubble.
The scheme - offering Government guarantees to allow buyers to secure properties with a 5% deposit - has been available for new-built homes from earlier this year, and was due to be extended to existing homes worth up to £600,000 from January.
But Mr Cameron said the Government was right to bring the second phase forward after receiving assurances last week from the Bank of England that there was no bubble.
"I am not going to stand back while people's aspirations to get on the housing ladder, to own their own flat, to own their own home, are being trashed," he told the Marr Show.
" If we don't do this, it will only be people with rich parents who can help them with the deposit who can get on the housing ladder. That is not fair, it is not right, it is not the sort of country I want to live in."
Shadow work and pensions secretary Liam Byrne said there were "big questions" over the second stage of the Help to Buy scheme, telling Murna ghan on Sky News: "House prices in London are growing at 10%. That feels to me like it is not sustainable.
"So what we are saying is let's get the Bank of England to look at the details of this scheme and let's ask them to opine on questions like why is the cap being set at £600,000? Is that too high?"
Chancellor George Osborne repeatedly declined to say whether Mr Cable had been consulted about the decision to bring forward the second phase of the scheme.
He told Pienaar's Politics on BBC Radio 5 Live he was "determined not to repeat the mistakes of the past" by allowing house prices to overheat the wider economy.
But he dismissed concerns about a bubble as London-centric, saying the idea of a boom would seem "very, very remote" for people in parts of the north west where prices had been falling.
Positive economic indicators meant the Prime Minister's party was in relatively buoyant mood as it gathered under the slogan "For Hardworking People", which was displayed on every possible surface in the Manchester Central conference centre. The annual conference began with a video tribute to former leader Margaret Thatcher, who died in April.
But Mr Cameron was aware he needs to shore up support with traditional Tories tempted by the UK Independence Party, as well as counter the popular appeal of Mr Miliband's energy freeze.
A YouGov survey for the Sunday Times suggested Labour was enjoying a significant post-conference bounce, with a healthy 11-point lead over the Tories by 42% to 31%, with Ukip on 13% and the Liberal Democrats 9%.
Tory chiefs were accused of trying to "stifle debate" after an advert for a fringe meeting featuring Ukip leader Nigel Farage failed to appear in the official conference guide.
And Foreign Secretary William Hague was dismissive of calls from some backbenchers for a formal arrangement between the two parties to co-operate in the 2015 election, telling Pienaar's Politics: " We don't make electoral pacts with other parties."
Both Mr Hague and Mr Cameron indicated that the renegotiation of the UK's EU membership which they have promised after the 2015 election will include withdrawing Britain from the commitment to seek "ever-closer union".
In moves apparently designed to shore up wavering right-wing support, Mr Cameron indicated he was ready to pull the UK out of the European Convention on Human Rights if it was necessary to keep Britain safe.
And the PM repeated Mr Osborne's position that a Conservative government would use spending cuts and not tax rises to complete the job of deficit reduction following the election.
"If we are going to get to grips with the problems with the cost of living people face, we've got to say to people we are not going to go on putting up taxes," said Mr Cameron. "The rest of the deficit reduction programme that George Osborne has set out we believe we can do by continuing to bear down on spending.
"I want to see us go on helping hard-working people, particularly low-paid people, to keep more of their money to spend as they choose."
Mr Cameron rejected reports that he had already discussed the possibility of a future Conservative/Liberal Democrat coalition with Mr Clegg.
"Every time I speak to Nick Clegg about the next election, it starts with me telling him that my aim is to put him out of a job," said the PM.
"I don't want another coalition, I want a Conservative-only government and I think that's what's right for the country."