Zamalek were banned from registering any new signings for two transfer windows and fined $200,000 after striking a new deal with youngster Hossam Ashraf while he had already signed for a Cameroonian academy.
Their hopes to have the ban lifted before the Egyptian transfer window closes were dashed when the Court of Arbitration for Sport (CAS) upheld it on Thursday.
Nagguez returned to Zamalek on a three-year deal last month after terminating his contract with Tunisian side Esperance, but he could not afford to stay out of action for an entire season after the club's ban was confirmed.
"It's important for me to play on a regular basis, that's why I joined Ahli," he said in a television interview.
Zamalek said they agreed with the 28-year-old to bring him back next summer.
Nagguez played for Zamalek from January 2018 until February 2019, participating in 64 games, scoring one goal and creating nine.
He was one of the main pillars of the team that won the African Confederation Cup and two Egypt Cup titles.
However, he left the White Knights in February 2019 in an acrimonious manner, unliterary annulling his contract over unpaid dues. Many Zamalek supporters opposed his return.