The number of offences involving actual or attempted online sexual communication with a child has quadrupled in Northern Ireland, campaigners said.
The NSPCC urged new laws to end the "Wild West" culture of the internet and tackle grooming on social media.
The PSNI recorded 82 offences last year (2017/18), compared with 19 the year before.
Policy manager for NSPCC Northern Ireland Colin Reid said: "Social networks have self-regulated and it's absolutely clear that children have been harmed as a result.
"We would urge the UK Government to follow through on their promise and introduce safety rules backed up in law and enforced by an independent regulator with fining powers.
"Social networks must be forced to design extra protections for children into their platforms, including algorithms to detect online grooming to prevent communicating with children from escalating into something even worse."
Girls aged between 12 and 15 were recorded as the victims in the majority of identified cases, the child protection charity said.
It is calling on the UK Government to: create mandatory safety rules that social networks are legally required to follow; establish an independent regulator to enforce safety laws and fine non-compliant sites; require social media sites to publish annual safety reports; and force platforms to develop technology to detect grooming using algorithms.
Following the NSPCC's #WildWestWeb campaign, the UK Government recently announced that laws will be brought in to regulate social networks, to keep children safe and prevent harms such as online grooming.
The charity is now campaigning to ensure those laws are sufficiently robust to truly keep children safe.
Mr Reid added: "It is important to remember that every single sexual message sent to a child is abuse, which can leave a lasting impact for years to come.
"We would also urge our local politicians, when we gain a new Executive, to think of a robust and workable e-safety strategy to drive this forward locally.
"We know that the online world is not easy to regulate, but we cannot be complacent when we are talking about child abuse."
PSNI Detective Superintendent Deirdre Bones said the rise was due to the fact that social media helped people communicate more easily with others and created opportunities for them to commit crimes online.
She said: "The internet can be a great place but it is important to remember there are people out there who may wish to abuse it.
"For parents worried about their children using the internet, our advice is to become net-savvy. The best safeguard against online dangers is being informed. Learn the basics of the internet and find out more about social media.
"Have conversations with your children - talk to them about the benefits and dangers of the internet and social media - so that you can empower them to use both safely.
"Get to know what they're interested in online and keep an eye on what they are doing. Find out what their favourite websites or social media platforms are and what online games they play."