The Cairo giants acquired Shikabala's services on the basis that he can not leave Egypt due to military service.
PAOK voiced their objection and took the case to the world governing body, who seemingly ruled in their favor.
"Zamalek have to pay the money within 30 days," PAOK said on their official website.
Zamalek chairman Mamdouh Abbas refused to comment.
"We are yet to receive anything from FIFA, we know nothing about this news," he told the club's website.
Huge Blow
The news, if true, will come as a huge blow to Zamalek coach Ruud Krol, who relies heavily on Shikabala's dazzling skills.
The 21-year-old playmaker has impressed since arriving at Zamalek, providing neat assists to his teammates as well as scoring goals himself.
It remains to be seen whether the men in white will be able to pay the money.
Although Zamalek are making attempts to sign new players in the January transfer window, their financial position is not that good.
The Egyptian League runners-up may be forced to halt Mohamed Abdallah's deal even though they announced he would arrive next month.