The PSNI has said it is working with partners in government and other agencies to "mitigate any risk to computer networks in Northern Ireland".
The police say organisations and individuals in Northern Ireland are being targeted on a daily basis by cyber criminals trying to steal data or commit fraud or blackmail.
About 200,000 victims in 150 countries or more have so far been affected by the cyberattack which occurred over the weekend.
As people return to work tomorrow after the weekend, many will have unopened, potentially infected emails in their inboxes, or their systems may already be infected and are waiting to activate.
Northern Ireland computer networks may have been infected by a virus that plunged parts of the NHS elsewhere in the United Kingdom into chaos, police have said.
The WannaCry ransomware virus infiltrates computers when users inadvertently download it by clicking on links or attachments in unsecure emails.
Payment is demanded within three days or the price is doubled, and if none is received within seven days the files will be deleted, according to the screen message.More news: Trump Taps Callista Gingrich to Be Ambassador to the Vatican
More news: Simona Halep takes on Kristina Mladenovic in Madrid Open final
More news: Google's Project Treble Might Actually Fix Slow Android Updates
There's only one confirmed case in Ireland so far - a healthcare unit in County Wexford - which the HSE says it's assisting but is not connected to its main network.
"All external emails have been blocked since Friday evening as a precautionary measure while security work is undertaken, and staff now have no access to emails", she said.
The HSE cut off its network from external communications as a precaution, on Friday.
The PSNI said its cyber crime centre would continue to actively participate "in the national co-ordinated response to this attack and we would encourage all local businesses and public services to take immediate steps to protect their systems and reduce their vulnerability".
Our version of the NHS, the HSE has been very proactive to ensure that it's business as usual for patients and all HSE employees ensuring that we don't face the issues that the NHS are facing.
"Ibec has previously called for adequate resourcing of the National Cyber Security Centre and the implementation of a cyber security programme".