The First Minister insisted it was for the people of Scotland - and not politicians - to decide when a fresh ballot on the issue should take place.
Ms Sturgeon spoke out as she campaigned in Uddingston in the run-up to the December 12 General Election.
Earlier on Tuesday, as the Scottish Conservatives launched their manifesto for that ballot, Scottish leader Jackson Carlaw suggested a gap of 40 years between referendums was a "fine definition" of what a generation should be.
In the run-up to the 2014 vote, SNP leaders told Scots the referendum would be a "once in a generation" event.
But with Ms Sturgeon now pressing for a second ballot in the later part of 2020, the Scottish Tory leader hit out, saying: "There are different definitions of a generation but I'll tell you what it ain't - it's not five years."
He added: "We had 40 years between the two European referendums. That seems like a fine definition."
Ms Sturgeon said: "I think the point Jackson Carlaw and Conservatives miss is this one - and it's a pretty basic point of principle - it's not up to Jackson Carlaw what the future of Scotland is.
"It's not up to me what the future of Scotland is either, it's up to the people of Scotland and it is not for any politician to set conditions or limits on the ability of any country to exercise its right to democracy."
The First Minister continued: "It's up to Scotland to decide if it wants to consider the question of independence again and it is up to Scotland to decide whether or not it wants to become an independent country.
"The Tories clearly have no respect for Scottish democracy at all, and the opportunity people in Scotland have in this election, for that reason and for many other reasons, is to make sure that the Tories are not in government after this election, that they don't have that majority they are seeking in order to give them the ability to call the shots."
With Boris Johnson having attacked the SNP's "crazy" policies on Europe - claiming under the First Minister an independent Scotland would have the euro as its currency - she hit back, branding the Prime Minister a liar.
She stated: "I'm going to be pretty blunt about this, Boris Johnson was telling lies. Some people may say not for the first time and perhaps not for the last time.
"But we have got a Prime Minister who has shown, since he came to office, that the truth is a disposable commodity for him, he gets up and says whatever comes into his head."
The SNP leader went on to brand Mr Johnson and his Conservatives a "real and present danger" to Scotland.
She said: "Boris Johnson poses a real threat to Scotland's future, a Boris Johnson government taking Scotland out of the European Union against our will, with all the damage that will do, is a real and present danger to Scotland's future prosperity."
Ms Sturgeon added: "This election is an opportunity to play our part in stopping that from happening. The SNP is the main challenger in every Tory seat in Scotland, so if people do not want Boris Johnson to be calling the shots of Scotland for the foreseeable future, then voting SNP to stop that happening is a priority."
She said that the SNP election manifesto - which she will unveil in Glasgow on Wednesday - would "set out very clearly our ambition and vision for Scotland".
Ms Sturgeon said the manifesto "will set out how the SNP, if we were to hold the balance of power in a hung parliament, would exercise that influence in a way that stands up for Scotland's interests, makes sure Scotland's voice is heard and pushes forward the kind of progressive policies I think most people across Scotland, and indeed many people across the UK, want to see".