According to the Daily Star, the 23-year-old model claimed that she hooked up with the athlete in her flat six days before Faryal announced that the couple were having a daughter.
Following the allegations, Khan tweeted: "Hahaha they make me laugh. As if I would touch you! #inyourdreams."
Faryal also took to Twitter to defend her relationship with her husband by describing the Bolton-born fighter as a "gem".
Khan's wife is due to give birth in a couple of months.