“Donald Trump, it has come to our attention that you want to ban all Muslims [from entering] the United States. This policy is going to have a huge impact," a person wearing a Guy Fawkes mask says in a video posted by the group.
The figure in the video continued by arguing that the Islamic State in Iraq and Syria (ISIS) wants the U.S. to ban Muslims from entering the country in an effort to make them more easily recruitable.
"The more the United States appears to be targeting Muslims, not just radical Muslims, you can be sure that ISIS will be putting that on their social media campaign," the person in the video says.
"Donald Trump, think twice before you speak anything. You have been warned," the figure adds.
The group said Friday it targeted a website for Trump Tower in New York, which was unable to be accessed by The Hill on Friday morning, saying the take-down was a "statement against racism and hatred."
Anonymous has launched similar attacks on other groups, as well as made public statements on issues surrounding race including the release of information on alleged Ku Klux Klan members last month.
It has been running an operation against ISIS, claiming thousands of social media accounts allegedly affiliated with the militant group, and has planned for a day of trolling Friday to combat ISIS.
Trump has stood by his proposal this week to temporarily ban Muslim foreign nationals from entering the U.S. amid stoked fears of terrorism, which have risen in polling to the level immediately after 9/11.