She was speaking to BBC Scotland on day two of the general election campaign.
Elsewhere, Scottish Labour launched a £175m Scottish anti-poverty fund.
The Scottish Lib Dems pledged £800m to improve the NHS in Scotland and the Scottish Conservatives criticised changes to stamp duty.
Voters across the UK go to the polls on 7 May.
On day two of the campaign, the main parties in Scotland will be pushing hard on their key messages.
Speaking on BBC Radio's Good Morning Scotland programme, Ms Sturgeon said another referendum was not an issue in this general election, but Trident remained a deal-breaker.
She said: "The general election is not about independence, it's about giving Scotland a louder voice in Westminster, making sure that Scotland's interests are protected and that the issues that matter to us are up the agenda.
"We're not going to get a referendum as a result of this Westminster election and that's not one of the issues that we would be seeking to secure."
But she insisted the renewal of Trident remained a "red line" issue for the SNP in any post-election deal with Labour.
Ms Sturgeon said: "Under no circumstance would we ever vote for the renewal of Trident or the spending of money on the renewal of Trident.
"In terms of any formal arrangement with Labour, I've made clear and I can't make clearer, Trident is a red line."
Labour leader Ed Miliband said earlier this month there would not be a Labour/SNP coalition in the event of a hung parliament.
Scottish Labour leader Jim Murphy pledged to establish a £175m fund aimed at "waging a war on poverty" during a visit to a food bank distribution centre in Edinburgh.
Mr Murphy said: "If it was not for the generosity of their fellow Scots, tens of thousands of people, including thousands of children, would be going hungry tonight.
"Scottish Labour promises to end the need for food banks. The causes of poverty are complex, which is why our plan is wide-ranging, from capping energy bills and banning rip-off rents to setting up a Scottish anti-poverty fund to provide practical help."
Ruth Davidson, Scottish Conservative leader, was also in the capital where she criticised the Scottish government's change to stamp duty and highlighted new figures which the Tories claim reveal the "true impact" of the new Land and Building Transaction Tax on home-buyers.
She said: "The Scottish Conservatives are the only party at this election which will campaign for a fair deal on tax for Scots. John Swinney has the funds to afford a tax cut for all homebuyers in Scotland.
"It's time he passed it on and ditched his tax on aspiration."
Meanwhile, healthcare was the focus for the Liberal Democrats' Scotland spokesman Alistair Carmichael as he visited a distillery in Inverurie.
He pledged an extra £800m for the NHS in Scotland, saying it was needed to tackle the extra pressures facing the health service from new treatments being available and people living longer.
But Mr Carmichael recognised that, because health is a devolved issue, it would be up the the Scottish government to decide whether the extra money would be spent on the NHS.
He said: "We value the NHS. We want to see it grown and adapt to the community it serves. That's why we're prepared to put our money where our mouth is."
What are the top issues for each political party at the 2015 general election?
Policy guide: Where the parties stand
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SNP leader Nicola Sturgeon has said another independence referendum would not form any part of a post-election deal with Labour, but the renewal of Trident remained a "red line".