2d A* pathfinding not jumping only flying and not use gravity

Here is my problem which is that I want to make my lower cube (enemy) use gravity and mass, and my cube never moves in straight down/Up in y-axis it just looks that cube is jumping down or jumping up on horizontal walls and follow the duck (Player). I am using "A* pathfinding". The image is for just understanding. Instead of using the red path the cube following the green path as shown in the image. I am very thankful in advance for helping me.