The Whites, who were 1-0 up in the first half at Green Mountain, couldn’t hold on to their victory as they lost second place to Ismaili.
"It was a below-par performance, in the second half the players were clearly out of form, we played a lot better in previous matches," the Dutchman said after the game.
"I am really disappointed because we lost our position as second of the table."
Krol defended his decision of playing out-of-fitness Tunisian defender Wissem El-Abdi, who was largely responsible for Telecom's equalizer.
"We missed players at the back, so we had to play El-Abdi, he is an international defender and should not be affected by lack of matches," Krol added.
El-Abdi was absent for long spells this season due to injuries and suspensions, as Zamalek are also missing defense duo Beshir Al-Tabie and Mahmoud Fathallah.