The call comes as it is predicted as much as €26 million will be spent on shopping in upcoming Black Friday sales.
New figures also show more than €45 million was stolen through frauds and scams in the second half of last year.
Speaking to RTÉ’s Morning Ireland, Detective Chief Superintendent Patrick Lordan, of the Garda National Economic Crime Bureau, said people need to be alert to online scams.
“We are warning all shoppers thinking of shopping online – even if they do it regularly – to be aware of the risk they are taking on Black Friday, Cyber Monday and on the run-up to Christmas,” he said.
“There are a lot of criminals out there setting up fake websites, setting up fake ads on social media, so you need to be aware of that and you need to be very alert to it.
“Don’t hand over your money to the first person you see on social media hoping that the product will be delivered.”
A new report shows fraudsters stole nearly €45 million from people in the second half of last year.
The figures, which are published by FraudSMART, the fraud awareness initiative led by the Banking and Payments Federation Ireland (BPFI), indicate a rise of 37% on the previous year.
The report also shows debit and credit card fraud (including ATM) hit €14.5m, up 18.5%, the highest levels since 2017.
Most of the increase was driven by online card fraud or “card not present” where a fraudster uses the victim’s compromised card information to make an online purchase.
Card fraud is returning to pre-pandemic levels
Last year also saw payment card fraud at “point of sale” or in-store return to pre-Covid levels as most retail outlets reopened with the lifting of most public health restrictions.
Head of Financial Crime with BPFI Niamh Davenport said card fraud is going back to pre-pandemic levels.
“It is at the highest levels it has been since 2017,” Ms Davenport said.
“We are going back to pre-pandemic levels and a lot of that is driven by pre-pandemic shopping.
“With Black Friday happening and the run-up to Christmas we are urging customers to take care.
“With all the restrictions lifted we are seeing fraud levels return to pre-Covid levels.
“Today’s fraud figures are a stark reminder that consumers need to be on high alert during what is the busiest online shopping period of the year.
“We know that fraudsters are continuously updating and adapting their tactics and tools.
“As well as scam texts, phone calls and emails, scammers have developed a range of techniques to convince online users to disclose key personal or financial information.
“While banks are using a range of measures such as encryption and continuous fraud monitoring to protect their customers and ensure every day payments can be made securely, fraudsters are increasingly targeting businesses and consumers directly, so it is important for us all to know how to protect ourselves.”
Ms Davenport added: “With a jump of almost 46% in debit card fraud losses alone, we are calling on all consumers to pause for thought before parting with their money or information and familiarise themselves with some of the very straight forward steps they can take to protect themselves.”
It is estimated Irish shoppers will spend €26 million on Black Friday this week, with 33% less expected to be spent on Cyber Monday.
Head of SME Banking at AIB John Brennan said the banks financial data predicts €18,000 per minute will be spent every minute on Black Friday.
This compares to €25,000 per minute last year.
He said the predicted reduction is down to changing shopping habits post-pandemic.
The AIB figures show clothing ranks first for consumer spending on Black Friday, followed by electronics, groceries, department stores and hardware.
“As people prepare for winter against a backdrop of cost of living increases, many are looking to complete their holiday shopping early and find Black Friday deals,” Mr Brennan said.
“AIB’s data shows that consumers are increasingly choosing online when it comes to grabbing a bargain on Black Friday.
“While this ensures more choice for consumers, it’s also important to consider the impact that buying from abroad can have on the climate.
“Shopping locally where possible ensures we are minimising our carbon footprint, and it supports local businesses.”
Det Chf Supt Lordan said people should contact their local gardai and bank if they suspect they have been scammed.