"Our manifesto will set out what we consider are the circumstances and the timescale on which a second referendum might be appropriate, but we can only propose, she was quoted by the BBC as saying.
At the same time, Sturgeon made it plain that the possible second referendum will only be staged if she believes that independence can be achieved.
"…If we are going to have another independence referendum I want to know there is support in Scotland for independence that means that referendum is going to be successful," she said.
She added that in the long run, this is for the people of Scotland to decide on whether to hold an independence referendum "in five years or 10 years or whenever."
Earlier, Sturgeon said that Scotland is being taken out of the EU against its will in the upcoming in-out referendum on UK membership, which could spark a second referendum on independence.
The SNP has, meanwhile, gained thousands of new members, winning 56 of Scotland's 59 seats in a general election in May 2016.
Opposition parties have repeatedly blamed Sturgeon for failing to deliver on her "once-in-a-generation" referendum promise.
