The attack - known as a DDoS attack - overloads websites and services to the point that they become unable to function.
Major banks have been hit in the past by similar attacks, and popular webpages and services such as Twitter, Spotify and Netflix have all been subject to recent attacks.
Hackers did not specifically say which service they would be attacking, however.
As well as targeting political campaigns and popular services, the hacking group has also campaigned against Islamic State in the past.
— Anonymous (@YourAnonNews) October 23, 2016
On Friday Twitter, Spotify and Netflix were targeted by hackers in a widespread cyber attack.
Users also reported being unable to access sites such as PayPal, Pinterest, AirBnB and PlayStation's online service.
US officials said they were investigating a DDoS attack.