The former Waterloo Road star, who is good friends with Tulisa Contostavlos, was set upon outside trendy DSTRKT in London on Wednesday night (24 July) as she chatted with her pals.
Following the incident, Chelsee apparently spoke to two police officers before bursting into tears in the street.
According to The Sun, the actress also tweeted: "So a girl thinks it's nice to punch me in the side of my head on the sly n run off lol. I seen u, you fat mess, wish I wuda caught u tub."
Chelsee has now deleted the tweet, although her fans have still been offering their support after reading reports.
One tweeted a message to her saying: "Hope you're ok after being punched by an idiot."
Another follower added: "Wow there really are some jealous people out there, f*** them and keep partying."
A girl also tweeted Chelsee saying she had heard about the incident and that she hoped she was ok. The actress replied: "Aww I'm cool thank you xx"
Chelsee's rep tells Reveal: "Chelsee was the victim of an unprovoked attack. We are not making any further comment."