"My client Babar Ali has served a legal notice on Akhtar over pretending injury in the decisive Test against India and over his reported nightclub bashes in India," Babar's lawyer Ansar Mahmood Bajwa said on Friday.
The fan demanded 100 million rupees (around 1.7 million dollars) in damages within 15 days, and threatened to take the case to court if damages were not paid.
Akhtar, the 28-year-old spearhead of Pakistan's bowling attack, failed to play the third day of the final Test against India on account of back and thumb injuries.
India won the Test and clinched their first ever Test series victory on Pakistani soil.
Cricket authorities are questioning the authenticity of his injuries following a wrist x-ray which suggested there was no damage.
Pakistan Cricket Board (PCB) chairman Shaharyar Khan told the BBC that PCB had formed a four-member medical commission headed by an orthopaedic surgeon.
"Akhtar pretended injury and let the whole nation down and then rubbed salt on the wounds with his off-field actions," the lawyer alleged.
Akhtar, who will feature for Durham county in the English season from next week, has denied faking injury.