The former Prime Minister has been accused of seeking to drag the Monarch into the political process after the bombshell revelations, but insists he did "nothing improper".
The Queen hit the headlines just four days before the historic vote when she urged Scots to "think very carefully about the future" as she greeted well-wishers outside Crathie Kirk after attending church near her Balmoral home. The remark was seized on by No campaigners.
But Mr Cameron told Radio 4's Today programme: "I never asked for anything improper to be said or done,
"The context of this which doesn't, I think quite come out of the programme is at the time Alex Salmond was going round saying that Her Majesty would be a proud Monarch of an independent Scotland.
"This concerned me because my side of the argument couldn't really say anything about that. So I had conversations with private secretaries and the like, but I never asked for anything improper to be said or done."
The former Prime Minister told the BBC he had sought support from the Queen during the referendum campaign after a poll predicting a Yes victory "panicked" him.
Mr Cameron made contact with Buckingham Palace officials in 2014, suggesting the monarch could "raise an eyebrow" in the close-fought campaign.
The former Tory Prime Minister has now hinted he may have revealed "too much" about his interactions with the Queen, but stressed he had not asked her to say or do anything improper.
He added: "I don't want to say anything more about this, I'm sure some people would think it may possibly even be that I have already said perhaps a little bit too much."
He said previous remarks he made at the time that the Queen had been "purring down the line" to him after the No result had been a "terrible mistake" for which he apologised immediately.
Mr Salmond has already hit out at Mr Cameron's intervention.
The ex-First Minister said: “Begging a constitutional monarch to make a political intervention is not only totally improper but an indication of how desperate Prime Minister Cameron was in the final stages of the Scottish referendum campaign.
"Five years on Scotland should remember that Westminster does not recognise any political rule book. Cameron started the campaign uber-confident and ended up in a blue funk. I doubt if Scotland will let the establishment off the hook next time around."
He added: "As to Cameron’s suggestion that he was successful in securing a royal intervention, I doubt that.
"What I can vouch for is that the week after the referendum I was asked to meet the Queen at Balmoral. We discussed Cameron’s “purring comments” to Michael Bloomberg in New York in the aftermath of the referendum where he again blurted out what he claimed were her private thoughts."