A £20m fund to teach Muslim women in the UK to speak English will tackle segregation and help them resist the lure of extremism, David Cameron says.
While there was no "causal connection" between poor English and extremism, language lessons would make communities "more resilient", Mr Cameron said.
But some Muslims have accused him of wrongly "conflating" the two issues.
The PM also suggested failing to learn English could affect people on spousal visas who wanted to settle in the UK.
The government says 22% of Muslim women living in England speak little or no English - a factor it argues is contributing to their isolation.
Segregation, the prime minister says, is allowing "appalling practices" such as female genital mutilation and forced marriage to exist, and increasing vulnerability to recruitment by so-called Islamic State - also known as Daesh.
He is also announcing a review of the role of Britain's religious councils, including Sharia courts, in an effort to confront men who exert "damaging control over their wives, sisters and daughters".
Speaking to BBC Radio 4's Today programme, Mr Cameron said the push on language was "about building a more integrated, cohesive, one nation country where there's genuine opportunity for people".
He said some "menfolk" in Muslim communities were fostering segregation by preventing women from learning English or leaving home alone, and that could not be allowed to continue.
There is "a connection with combating extremism" too, he argued, and improving English was important "to help people become more resilient against the messages of Daesh".
"I'm not saying there's some sort of causal connection between not speaking English and becoming an extremist - of course not, that would be a ridiculous thing to say," he continued.
"But if you're not able to speak English, you're not able to integrate, you may find, therefore, that you have challenges understanding what your identity is and you could be more susceptible to the extremist message that comes from Daesh."
New rules will mean that from October, people coming to the UK on a five-year spousal visa will have to take a test after two and a half years to show they are making efforts to improve their English.
Asked what would happen to those who failed, Mr Cameron told Today: "They can't guarantee that they'll be able to stay.
"It is tough. But in the end it is not enough just to say the government is going to spend more money and it is our responsibility. People coming to our country, they have responsibilities too."
The BBC's political correspondent Alex Forsyth said the government was absolutely not suggesting people could be deported if they failed to reach the required level, but that language skills would be one factor taken into account when deciding whether to extend a person's right to remain.
Dal Babu, a former chief superintendent with the Metropolitan Police who now works with families whose children have gone to fight with IS, told Today the investment in language lessons was welcome.
But he added: "My concern is how we have conflated the issue of learning English with stopping radicalism and extremism... to conflate the two is unhelpful."
Mr Babu also said he did not recognise the figure of 22% as the proportion of Muslim women without good English - instead quoting a figure of 6%, cited by racial equality think tank the Runnymede Trust.
Dr Sundas Ali, a lecturer at Oxford University who researches Muslims in Britain, said language might be a barrier for some women, but there were much bigger factors.
"I think there's an overall cultural problem in a lot of the Muslim community which is of low expectations. I think Muslim women are not encouraged as much as non-Muslim women to excel in their education and their careers."
She added: "Overall, I see what he [David Cameron] is trying to do and I do appreciate that, but I think there are other issues affecting Muslim women which he should have mentioned, such as hate crimes."
The Muslim Council of Britain welcomed the plans for language tuition but said it was wrong to single out Muslim women as other minorities "also struggle with English".
MCB secretary general Shuja Shafi also questioned whether linking the issue of extremism to the announcement was valid.
The language lessons will be targeted at "specific communities" identified by a review into segregation that is being conducted by Louise Casey, head of the government's "troubled families" unit.
They will take place in homes, schools and community facilities, with travel and childcare costs - described as "some of the greatest barriers to participation" - being covered. An existing scheme is said to have helped more than 30,000 adults.
The PM acknowledged cuts had been made to free language classes for immigrants during the last Parliament, but said the new £20m fund was "more targeted".