US presidential hopeful Donald Trump is making it more difficult to confront and defeat extremists, David Cameron has said.
The billionaire is making the "fundamental mistake" of trying to blame all Muslims for the ideology of a minority, the Prime Minister insisted.
Mr Trump, who is vying to win the Republican nomination, sparked widespread anger after he demanded a block on Muslims entering the US and claimed parts of London were "so radicalised" police were "afraid for their own lives".
MPs spent three hours debating whether the tycoon should be allowed into the country after more than 570,000 people signed a petition asking the Government to ban him on hate speech grounds.
Mr Cameron's warning comes after he last year branded Mr Trump's remarks as "divisive, stupid and wrong".
The interventions are likely to put diplomatic relations between Britain and the US under significant strain if the businessman is elected in the November poll.
Mr Cameron told US website Mic.Com: "I think the problem with what Donald Trump has said, and what some others say too, is they are making a fundamental mistake of trying to blame all of Islam and all Muslims for what is the ideology and the actions of a minority, and I think that's wrong.
"In many ways, it actually helps the extremists, because they want to create a clash of civilisations between Islam and Christianity, or Islam and the West.
"Actually, what's happening is not a clash of civilisations.
Donald Trump's most controversial quotes
Donald Trump's most controversial quotes
1/14 On Isis:
"Some of the candidates, they went in and didn’t know the air conditioner didn’t work and sweated like dogs, and they didn’t know the room was too big because they didn’t have anybody there. How are they going to beat ISIS?"
2/14 On immigration:
"I will build a great wall — and nobody builds walls better than me, believe me —and I’ll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words."
3/14 On Free Trade:
"Free trade is terrible. Free trade can be wonderful if you have smart people. But we have stupid people."
PAUL J. RICHARDS | AFP | Getty Images
4/14 On Mexicans:
"When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems. They’re bringing drugs. They’re bringing crime. They’re rapists."
5/14 On China:
"I just sold an apartment for $15 million to somebody from China. Am I supposed to dislike them?... I love China. The biggest bank in the world is from China. You know where their United States headquarters is located? In this building, in Trump Tower."
6/14 On work:
"If you're interested in 'balancing' work and pleasure, stop trying to balance them. Instead make your work more pleasurable."
7/14 On success:
"What separates the winners from the losers is how a person reacts to each new twist of fate."
8/14 On life:
"Everything in life is luck."
9/14 On ambition:
"You have to think anyway, so why not think big?"
10/14 On his opponents:
"Bush is totally in favour of Common Core. I don't see how he can possibly get the nomination. He's weak on immigration. He's in favour of Common Core. How the hell can you vote for this guy? You just can't do it."
11/14 On Obamacare:
"You have to be hit by a tractor, literally, a tractor, to use it, because the deductibles are so high. It's virtually useless. And remember the $5 billion web site?... I have so many web sites, I have them all over the place. I hire people, they do a web site. It costs me $3."
12/14 On Barack Obama:
"Obama is going to be out playing golf. He might be on one of my courses. I would invite him. I have the best courses in the world. I have one right next to the White House."
13/14 On himself:
"Love him or hate him, Trump is a man who is certain about what he wants and sets out to get it, no holds barred. Women find his power almost as much of a turn-on as his money."
14/14 On America:
"The American Dream is dead. But if I get elected president I will bring it back bigger and better and stronger than ever before and we will make America great again."
"It is a fight within Islam, where the overwhelming majority rightly see Islam as a religion of peace, and want to live in successful multi-racial, multi-ethnic, multi-faith democracies like ours, and make an incredible contribution to our country.
"As opposed to a small minority that believe this rhetoric of poisonous extremism, and many of this tiny minority then believing in violence.
"So, what Donald Trump says is, in my view, not only wrong, but actually it makes the work we need to do to confront and defeat the extremists more difficult."