The Egypt international was filmed on a mobile phone from a section of home supporters as he was taking a corner during Monday night's Premier League match against the Irons.
The video clip contains audible expletives directed at the Liverpool player, including comments against his Muslim religion.
The user who posted the video on Twitter said: "I was disgusted by what I was hearing. People like this deserve no place in our society let alone football matches. #kickracismout"
Having been tagged in the social message post, the Football Association were made aware of the video, which was shared with West Ham for investigation as a matter of urgency, reports claim.
West Ham are taking immediate action to identify the individual, or individuals concerned, and intend to hand their details over to the police so they can be banned from attending football matches.
The Metropolitan Police are also reviewing the footage.
A West Ham spokesperson said: "At West Ham United, we have a zero tolerance policy to any form of violent or abusive behaviour. We are an inclusive football club.
"Regardless of age, race, religion or belief, marriage or civil partnership, pregnancy or maternity, sex, sexual orientation, gender reassignment or disability, everyone is warmly welcomed at London Stadium.
"Anyone identified committing an offence will have their details passed to the police and will face a lifetime ban from London Stadium. There is no place for this kind of behaviour at our stadium."