He said he still favoured the use of Sterling, but said the independence case needs "refurbishment".
The MP believed a better case for the retention of the pound would prevent the independence case being "gazumped" by opponents in a future referendum.
Had Scotland voted "Yes", the planned independence day would have been 24 March.
When asked by BBC Scotland's political correspondent Glenn Campbell about the pro-independence camp's stance on currency, Mr Salmond said: "I think the argument you have got to put forward is one which can withstand any position adopted by your opponents.
"So, you mustn't allow yourself to be gazumped by your opponents.
"Now, I think sterling is the right currency for Scotland, because of a whole range of reasons that we gave during the campaign."
The former SNP leader was speaking a matter of weeks after current leader and Scotland's first minister, Nicola Sturgeon, announced plans for a fresh campaign for independence.
She told her party's spring conference in Glasgow, that she would hear "concerns" and "address questions".
In September 2014, voters north of the border decided by 55% to 45% to stay part of the United Kingdom.
The SNP's new strategy will begin in the summer, after May's Holyrood election and June's EU referendum.
Ms Sturgeon said the party was prepared to challenge some of the answers it gave 18 months ago.
Reacting to Mr Salmond's comments, Scottish Labour's Iain Gray said: "As far as I can make out he seems to be arguing again for Sterlingisation, a proposal that would have meant Scotland would have become an independent country and at that very moment given up control over its currency and much of its fiscal policy.
"That didn't make sense in 2014, the majority of the Scottish public didn't think it made sense, and it still doesn't make sense now."
Scottish Conservative leader Ruth Davidson said Mr Salmond had "a bit of a cheek" in "acknowledging 18 months after the fact that his currency case was always flawed".
She said: "People in Scotland have been well served by the pound as part of the UK, particularly with all the shocks and instability we've seen over the last few years in the world economy.
"If there is a united push from the SNP to get us back to yet another referendum, I'll be standing full square behind the decision that we as a country made to stay part of the UK."
Scottish Lib Dem leader Willie Rennie said it was time to move on from the whole matter to focus on the "big challenges".
He added: "There's no doubt that currency was one of the weakest arguments during the referendum. But the SNP need to move on - we all need to move on from the last five years. It was dominated by independence.
"If we keep dragging over the coals from yesterday's argument, we'll never sort out the future."
Scottish Green Party co-convener Patrick Harvie said it was "welcome" and "probably almost inevitable" that the SNP would re-evaluate its position on the pound.
He went on: "That idea of a currency union failed to convince us, because Scotland would have been in a situation where it didn't have the freedom to set its own economic policy. There were a great many Yes voters who were not sold on that notion of a currency union.
"It's inevitable that there were many people who might ultimately have been persuaded to vote yes, who voted no, and one of the reasons was the lack of clarity on currency."
Former first minister Alex Salmond has called for a fresh look at the currency options for an independent Scotland.