The proposed amendments would also allow NSW Police to seek apprehended violence orders in response to serious online abuse.

"Modern technology requires modern laws," state Attorney-General Mark Speakman told reporters in Sydney on Sunday.

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"This is not about protecting people's injured feelings. This is about protecting people against potentially devastating psychological and tragic consequences."

Police Commissioner Mick Fuller says technology allows people to harass others 24/7 using computers and smartphones.

"These changes give NSW Police the power to attack these offenders back in their homes," he said.

"We (will) have the power to arrest them and also take out apprehended violence orders that include this type of cyberbullying."

The government is essentially clarifying the Crimes Act to make clear that online activity can amount to stalking and intimidation.

The law would complement federal legislation but have tougher penalties - a five-year maximum as opposed to three years for the commonwealth offence.

The attorney-general says the NSW changes will cover conduct by juveniles but he expects children's courts would usually put young offenders into diversionary programs rather than prison.

The state opposition will back the changes but Labor leader Luke Foley wants the government to focus on prevention not just punishment.

"There ought to be a blanket ban on smartphones and watches for primary school children," he told reporters.

"For high school children ... there should be some very severe restrictions."

Domestic Violence NSW chief executive Moo Baulch says the government's approach will send a clear message.

"We know up to 98 per cent of victims of family and domestic violence have experienced online abuse - it's a devastating crime that follows people into their homes," she told reporters.

"It can feel almost inescapable when you're being stalked, bullied and harassed online."