It reads: "The current welfare and diversity officer has used hate speech based on race and gender.
"For example, the consistent use of hashtags such as #killallwhitemen and #misandry, and publicly calling someone 'white trash' under the official GSU Welfare and Diversity Officer Twitter account."
The twitter account has since been shut down.
Ms Mustafa's ban on white people and men from the meeting was made public last month.
She had written on Facebook: "Invite loads of BME [black and minority ethnic] Women and non-binary people!! Also, if you've been invited and you're a man and/or white PLEASE DON'T COME just cos i invited a bunch of people and hope you will be responsible enough to respect this is a BME Women and non-binary event only."
Non-binary is a term used to describe people who do not consider themselves exclusively male or female.
Miss Mustafa, 27, added: "Don't worry lads we will give you and allies things to do", followed by a wink.
The event's online page said it was open to "self-defining BLACK and ETHNIC MINORITY women and non-binary people with gender identities that include "woman'."
A notice about the meeting later appeared to show the ban had been dropped, stating: "Allies now welcome!"
The post was met with outrage by students of the university, one of whom described the exclusive policy as "patronising beyond belief".
Ms Mustafa has previously defended her position on her ban in a video clip, where she said in a statement read out to her fellow students that ethnic minority women could not be racist as they "do not stand to gain" from inequality.
She also accused the media of embarking on a "witch hunt and shameful character assassination".
If three per cent of students' union members sign the petition, Ms Mustafa will be subject to a vote of no confidence. She will lose her role if two thirds of those who vote say she should be removed from the post.
In her response to the no confidence petition, Ms Mustafa admitted that using the phrase "white trash" on an official account was "not professional", but said the hashtags had been used as a joke.
She wrote: "Regarding my use of hashtags: these were done on my personal account, which is separate to my work account.
"However, I still recognise and understand how this can be alienating and troubling to some.
"These are in-jokes and ways that many people in the queer feminist community express ourselves it's a way of reclaiming the power from the trauma many of us experience as queers, women, people of colour, who are on the receiving end of racism, misogyny and homophobia daily.
"These are not political stances. However, in regards to calling someone "white trash" under my official GSU Welfare and Diversity twitter account, I can accept that it was not professional and I do apologise for this."
She also said that she had received racists and sexist abuse, as well as death threats, "since the media storm" over her comments.
Miss Mustafa recently graduated from Goldsmiths with an MA in gender and media studies.
She is understood to live with her mother Nursen, 55, father Ismail, 57, and sister Ipek, 23, in Enfield in a £450,000 three-bedroom terrace.
