A temporary block to Facebook in Nauru is to protect children from abuse and is not linked to asylum seekers in an Australian-run detention centre, Nauru's president says.

"This decision has been made by government to protect its people from the abuse of the internet which has seen vulnerable individuals, especially young Nauruan girls, being maliciously targeted, harassed and even bullied," president Baron Waqa said in a statement.

"It is part of the government's efforts to curb the glorification of criminal activities and offences against Nauruan women and children through the posting of distressing images and footage of these individuals in compromising and dehumanising positions."

Nauru's government recently said it was restricting internet access in a bid to block pornography, especially child pornography.

But refugee advocates said the ban was designed to restrict asylum seekers in detention on Nauru from communicating with the outside world.

Mr Waqa said it was wrong to link the issue of refugees to the ban, saying asylum seekers had "plenty of email and social media options".

Opposition MP Matthew Batsiua had said the move was a way of stopping Nauruans from using Facebook to criticise the government.

"The first reason they gave [for the closure] was due to a technical problem. Now it's all about porn," he said.

"This is all about [justice minister] Adeang and his cronies being worried about the ever increasing number of people who have taken to social media to criticise his dictatorial style, which even the president is either unwilling — or too scared — to rein in."

Mr Waqa rejected the allegations.

"I am surprised by comments made by members of the opposition who seem more interested in politicising the issue and pushing their own agendas, than the welfare and protection of our people," he said.

Mr Waqa said the decision was made after "several months of investigation" and sites like Facebook were "under a temporary block" while the government worked to resolve the issue.

"At Facebook, we take the safety and well-being of the people who use our services very seriously," a Facebook spokeswoman said.

"Content that is pornographic, bullying and harassment or that invades someone's privacy is expressly prohibited by our terms of service, and we promptly review and remove all content that is reported to us that violates our policies."

ABC