The First Minister claimed the Prime Minister "personifies" everything that is currently wrong in British politics. He also said Mr Cameron is a "substantial liability" to the No campaign.
The TNS Scotland survey of just under 1000 people aged over 16 placed the No vote up one point on a month ago at 42%.
The Yes vote is also up one point, on 30% - a lead for the Nos of 12 points. Those who cannot decide who to back were down two points but were still comparatively high on 28%.
Among those who said they were certain to vote, those in the anti-independence camp were on 44% while those in favour were on 35%; a further 20% said they were undecided.
This nine-point lead is well down on the 22% lead recorded in September.
With four months to go before the referendum on September 18, 53% believed the Better Together campaign had been negative with 15% disagreeing, while 29% felt the Yes Scotland campaign had been negative with 37% disagreeing.
Even among the No voters, more agreed than disagreed - 41% to 26% - that the Better Together campaign, led by Labour's former Chancellor Alistair Darling, had been negative.
Among those who said they had yet to make up their mind, just under half (45%) said the anti-independence campaign had been negative compared to 24% who considered the same of the pro-independence campaign.
Tom Costley, the head of TNS Scotland, said: "As the electorate usually claims to dislike negative campaigning, this poll suggests Better Together may need to consider adopting a more positive tone to its campaigning in the run-up to September 18."
Yes Scotland chief executive Blair Jenkins described the results as "extremely encouraging". Better Together campaign director Blair McDougall said the poll showed they retained "a strong lead" but added there was no complacency.
The snapshot also found that more voters felt they were getting the information they needed to make an informed choice.
Almost half of those polled (49%) indicated they had received enough information. This was up from last October when three in 10 said they were satisfied they knew enough.
Yes voters were more likely than No voters to say they felt sufficiently informed - 68% versus 53% - while 45% of undecideds said they still did not have enough information.
Mr Salmond predicted that Mr Cameron's impending trip north would be "counter-productive" as it would continue the "same rut of negativity".
"Scotland has moved beyond the fearmongering of David Cameron," declared Mr Salmond.
"He personifies everything that's wrong with the politics in this country at the present moment, where a Tory prime minister with minimal, negligible support in Scotland can command political authority over our country, a country which has never and will never elect people like him to govern us. That is the democratic deficit, which is one of the key arguments, which is propelling the Yes campaign forward."
The Coalition hit back with a senior Whitehall source, noting how negative the SNP leader's remarks were.
"More people in Scotland voted for the parties of the UK Government in the General Election than voted Alex Salmond for First Minister a year later.
"It is up to him if he wants to play the man but we will continue to play the ball and set out the positive case for Scotland," he added.
Meantime, Downing Street again defended Mr Darling's leadership of the No campaign after suggestions that the Edinburgh MP had been "effectively dumped" as the frontman for Better Together.
After the campaign itself dismissed reported concerns - attributed to Mr Cameron's inner circle - as "absolute tripe", the PM's spokesman made clear Mr Cameron continued to believe completely that Mr Darling was the right man to lead Better Together.
Asked if the Prime Minister had any doubts about the ex-Chancellor's leadership, he replied: "None whatsoever," branding the reports "just wrong".
The spokesman added: "I very much look forward to Alex Salmond debating with Alistair Darling and look forward to hearing from Alex Salmond when he is going to do that."
Elsewhere, Sir Malcolm Bruce, the Scottish Liberal Democrat President, seized on remarks from Jim Sillars, the former Nationalist Deputy Leader, who suggested Mr Salmond had "become a liability", as well as a poster, produced by Yes supporters, that dismissed the role of the First Minister in the pro-independence campaign.
The veteran MP claimed the independence case appeared to be falling apart. "Yes supporters seem to be losing faith in Alex Salmond," he said.
In a separate development, Deutsche Bank, the world's largest foreign exchange dealer, argued the political uncertainty after a Yes vote was "likely to be negative" for sterling.
Standard Life today confirmed plans to move Scottish jobs south if Scotland votes to leave the UK.