The five-time winners, who beat Ghana 2-0 in the 2017 semi-finals, went closest in the first half as Christian Bassogog was denied by Richard Ofori.
But Ghana almost won it late on when substitute Owusu Kwabena struck the crossbar and Andrew Yiadom went close.
Clarence Seedorf’s side are two points clear at the top of the group before Benin play Guinea-Bissau (21:00 BST).
With four of the six third-placed teams qualifying for the knockout stage, Cameroon are well placed to reach the last 16 after starting their defence with a 2-0 win over Guinea-Bissau while Ghana were held to a 2-2 draw with Benin in their opener.
Ghana started better in a first half of few chances in Ismailia, with defender Kasim Nuhu shooting over following a corner before Christian Atsu sent a long-range strike just wide, but the Newcastle winger was injured in the process and replaced by Samuel Owusu, who then dragged a shot well wide.
Cameroon almost broke the deadlock five minutes before half-time after Ghana’s Chelsea left-back Baba Rahman was caught in possession by Bassogog just inside his own half.
Bassogog, who was named player of the tournament in 2017, played the ball down the right for Karl Toko Ekambi before racing on to his cut-back, but goalkeeper Ofori leapt across his goal to make a fine save.
Ghana’s Mubarak Wakaso twice fired wide after the interval while Bassogog’s goal-bound volley struck Jonathan Mensah on his chest.
And Ghana almost won it as Kwabena fired against the top of the crossbar after cutting out a poor pass by Cameroon defender Jean-Armel Kana-Biyik, while Reading full-back Yiadom had a shot saved by Ofori.