Catholics do not have to breed “like rabbits” and should instead practise responsible parenting, Pope Francis said on Monday.

Speaking to reporters en route home from the Philippines, Francis said there were plenty of church-approved ways to regulate births.

But he firmly upheld church teaching banning contraception and said no outside institution should impose its views on regulating family size, blasting what he called the “ideological colonisation” of the developing world.

African bishops, in particular, have long complained about how progressive, western ideas about birth control and gay rights are increasingly being imposed on the developing world by groups, institutions or individual nations, often as a condition for development aid.

“Every people deserves to conserve its identity without being ideologically colonised,” Francis said.

The pope’s comments, taken together with his defence of the Catholic church’s ban on artificial contraception during the trip, signal that he is increasingly showing his more conservative bent, which has largely been ignored by public opinion or obscured by a media narrative that has tended to highlight his populist persona.

On the trip, Francis gave his strongest defence yet of the 1968 encyclical Humanae Vitae, which enshrined the church’s opposition to artificial birth control. He warned against “insidious attacks” against the family — a reference to gay marriage proposals — echoing language often used by overwhelmingly conservative US bishops. And he insisted that “openness to life is a condition of the sacrament of matrimony.”

At the same time, however, he said it’s not true that to be a good Catholic “you have to be like rabbits”. On the contrary, he said “responsible parenthood” requires that couples regulate the births of their children, as church teaching allows. He cited the case of a woman he met who was pregnant with her eighth child after seven cesarean sections.

“That is an irresponsibility!” he said. The woman might argue that she should trust in God. “But God gives you methods to be responsible,” he said.

He said there are many “licit” ways of regulating births that are approved by the church, an apparent reference to the natural family planning method of monitoring a woman’s cycle to avoid intercourse when she is ovulating.

During the Vatican’s recent meeting on the family, African bishops denounced how aid groups and lending institutions often condition their assistance on a country’s compliance with their ideals: allowing health care workers to distribute condoms, or withdrawing assistance if legislation discriminating against gays is passed.

“When imposed conditions come from imperial colonisers, they search to make people lose their own identity and make a sameness,” he said. “This is ideological colonisation.”

The Pope also announced that his US trip in September would be limited to Washington, New York and Philadelphia and that he would not go to California to canonise Junípero Serra, the 18th-century Spanish Franciscan priest who founded missions there.