"I don't want to prejudge the outcome, but I would note that so far it has not found any evidence to contradict the insistence by senior Indian army commanders responsible at the time that the responsibility for this was carried out solely by the Indian army," he told Parliament.
Cameron's remarks came while fielding questions from opposition MPs on claims that the country's Special Air Services (SAS) commanders helped out with the military operation to flush out Sikh militants holed up in the Golden Temple on orders of former Prime Minister Margaret Thatcher.
"I think it is important to put that, but it is important to get to the bottom of this...the findings of the official inquiry into the incident will be made public," Cameron said, a day after ordering an urgent probe into the decision by Thatcher's government in 1984.
Cameron has asked Cabinet Secretary Jeremy Heywood to conduct the investigation after documents declassified suggested a British special forces officer advised the Indians on carrying out the attack.
The claims have emerged from documents released by the National Archives in London under the 30-year declassification rule as part of the series over the New Year.
Labour MP Tom Watson and Pat McFadden had raised the issue in the House of Commons, demanding full disclosure of the issue.
Watson and Lord Indarjit Singh had demanded an explanation after the documents made public indicated that the officer of Britain's SAS was dispatched to help India plan for the raid on the Golden Temple, an operation that left over 1,000 people dead.
Cameron said the assault had left "deep scars" and "incredibly strong feelings that exist to this day".
Sikh groups in the United Kingdom have claimed the latest developments prove a deeper controversy that they had always suspected.
A "top secret and personal" letter, dated February 23, 1984, nearly four months before the raid in Amritsar, and titled "Sikh Community", stated: "The Indian authorities recently sought British advice over a plan to remove Sikh extremists from the Golden Temple in Amritsar.
"The Foreign Secretary decided to respond favourably to the Indian request and, with the Prime Minister's agreement, an SAD (sic) officer has visited India and drawn up a plan which has been approved by Mrs Gandhi. The Foreign Secretary believes that the Indian Government may put the plan into operation shortly," the letter said.
The file, contents of which have been seen by PTI, also contains notes on some missing letters dated February 3, 23 and 27, 1984, which have been "retained under Section 3(4) of the Public Records Act of 1958".
"These documents prove what Sikhs have suspected all along, that plans to invade the Golden Temple went back months even though the Indian government was claiming even weeks before that there were no such plans," Lord Singh, the director of the Network of Sikh Organisations in the United Kingdom who also plans to raise the issue in the House of Lords, said.
Five months after Operation Bluestar, former Indian Prime Minister Indira Gandhi was assassinated by her Sikh bodyguards in retaliation for the raid on the Golden Temple.