The video, which was made public last month, appeared to show Cooper being denied backstage access at a music concert before using the word "nigger" to describe one of the bouncers.
The 25-year-old, who has since been suspended from all team activities as he seeks counselling, was subject to abuse on Twitter, and the Eagles have alerted NFL security to the situation.
"Riley Cooper made us aware of the tweets when the video became public," read a team statement. "He told us that he did not know about the video.
"He informed us he blocked the tweets because he did not know the person nor understand the context of what that person was threatening. We promptly alerted NFL security.
"This information potentially speaks to a legal issue that is a matter between Riley and the authorities. Our focus has been on Riley's words and actions."
Cooper was chosen by the Eagles in the fifth round of the 2010 draft and has since gone on to score five touchdowns.