The Atlas Cubs' goals were scored by Amir Richardson (19’), Sofiane Rahimi (28’) and Abdessamad Ezzalzouli (36’).
Following this victory, Morocco top their group with 6 points, ahead of Argentina that beat Ukraine 2-0, on goal-average.
Morocco will face, in the quarter-finals scheduled for next Friday, the runner-up from Group A, which includes France, Guinea, the United States and New Zealand.