David Cameron fears a "witch-hunt" against gay people by those commenting online about child abuse allegations.
The prime minister made his comment on This Morning after being unexpectedly handed a list of names of people, who the ITV1 show's presenter said were being mentioned online as paedophiles.
The PM was addressing historic claims of a paedophile ring linked to No 10.
Mr Cameron did not rule out one inquiry into abuse claims but said the priority was to "get to the truth" quickly.
The allegations were raised by Labour MP Tom Watson in the Commons a fortnight ago.
There have also since been claims by a victim that an unnamed, prominent Conservative politician from the Thatcher era was involved in abuse in north Wales.
This Morning presenter Phillip Schofield told the prime minister there were lots of allegations circulating online about people who might have carried out abuse.
Mr Cameron said he had heard "all sorts of names being bandied around".
The prime minister is said to be disgusted that "old online gossip" about some politicians covering up the fact they were gay was now being associated with the serious crime of child abuse.
During the live interview, the presenter handed the PM a card with a list of names on it, saying that they were people Mr Cameron knew and asking whether he would be talking to them.
Mr Cameron, who did not look at the names, replied with a warning: "There is a danger, if we're not careful, that this could turn into a sort of witch-hunt, particularly against people who are gay and I'm worried about the sort of thing you are doing right now - giving me a list of names that you've taken off the internet."
Phillip Schofield's actions were criticised by two senior politicians appearing on the BBC's Question Time on Thursday night.
Policing Minister Damian Green described it as a "pretty tasteless and silly stunt".
"He shouldn't have done it," Mr Green said. "What the prime minister was warning about was - if we start plastering names all over the place, of which there may be no evidence, it may well turn into a witch-hunt."
On the same programme shadow business secretary Chuka Umunna said: "I think what Phillip Schofield did was foolish, stupid and grossly irresponsible - and frankly rather amateur.
"It's not what you expect of serious broadcast journalism."
A senior aide to the prime minister said blameless people who were not connected to any child abuse investigations currently being carried out were being targeted by online gossip.
It was "important allegations are handled properly - and people's reputations are not unnecessarily smeared", added the source.
A No 10 source also described the decision to hand Mr Cameron the list of names as a "silly stunt" and "irresponsible".
Conservative MP Rob Wilson has reported the programme to broadcasting regulator Ofcom, urging them to investigate whether ITV1 had breached its duty to give individuals a chance to respond before subjecting them to serious allegations on-screen.
Mr Schofield later apologised if the names on the card could be seen by viewers because of a "misjudged camera angle".
"If any viewer was able to identify anyone listed, I would like to apologise and stress that was never my intention. I was not accusing anyone of anything and it is essential that it is understood that I would never be part of any kind of witch-hunt."
A string of official inquiries has been launched into child abuse since allegations about the activities of the late BBC television presenter Jimmy Savile.
Home Secretary Theresa May has already announced a new police inquiry into allegations of child abuse in north Wales in the 1970s and 1980s.
Mrs Justice Macur will also investigate the terms of the 1996 Waterhouse inquiry over alleged child abuse in north Wales.
The Conservative Party has confirmed it is investigating reports linking one of Margaret Thatcher's former close aides to the allegations.
Asked about Labour's call for a single over-arching inquiry, Mr Cameron said: "The idea that if you had one mega-inquiry that you would speed everything up, I'm not sure is true.
"I don't rule out taking further steps. I want the government to be absolutely on top of this. I don't want anything to be covered up, I don't want any information to be held back, if there are more things we have to do, we will do them."
"But we always have to remember it's very easy for governments just to stand up and say 'Here's a new inquiry'. What we've got to do is get to the truth as fast as we possibly can."
Child protection charity the NSPCC has called on the government to commit to an over-arching "lessons learned" review to pull together the findings from all the current inquiries into child abuse, once they are completed.
In conjunction with the Child Exploitation and Online Protection (Ceop) centre and the Serious Organised Crime Agency (Soca), the NSPCC has set up a helpline for those affected by the north Wales abuse. The number is 0800 389 6176.
With the caller's consent, information will be passed on to the Child Exploitation and Online Protection Centre. Alternatively, those affected can visit the NSPCC's online helpline.
Correction 10 November 2012: The BBC has apologised unreservedly for broadcasting a report on Newsnight on 2 November over allegations of child abuse which transpired to have involved a case of mistaken identity. As a result the video of the original report has been removed from the website. More details can be found here.