كتب : Hatem Maher
The towering frontman headed home eight minutes past the hour mark to lift Zamalek past the resilient second-division side and give them a place in the competition's round of 16.
He put his finger to his lips in front of the home fans, who sang offensive chants against the Cairo giants.
"Those fans kept insulting us throughout the game in bizarre fashion," Gaafar told FilGoal.com on Sunday.
"They also hurled stones at us for no reason, their actions were very provocative."
Zamalek coach Hossam Hassan also hit out at the fans for verbally abusing him during the game.
He said they were supporting Zamalek's arch-rivals Ahli instead of cheering Fayoum and called on the Egyptian FA to punish them.
Derby Promise
Zamalek will face Ahli in the Egyptian Cup round of 16 on Wednesday at Cairo Stadium for their third derby clash this season.
Their first league meeting ended in a goalless stalemate but the second was a much more interesting affair.
Zamalek took the lead three times but Ahli eventually managed to secure a share of spoils after Mohamed Barakat struck home in stoppage time to give the Red Devils a 3-3 draw.
Gaafar scored the opener in that game and is determined to notch his second derby goal on Wednesday.
"I promise Zamalek fans that I will score against Ahli again," the 24-year-old added.
Gaafar is Hassan's preferred choice upfront. He usually plays as a lone striker in front of attacking midfielders Shikabala, Alaa Ali and Hussein Yasser.
He was Zamalek's top scorer in the league with nine goals as the team finished runners up to champions Ahli.