prevent actors from rotating (2D side scrolling preset)

Good day, i’m having a problem with some of the actors i have in my game. These actors are simply the enemies you will face in the game. The problem is that these actor rotates around the y-axis and fell into the ground (See video!!!).
How can I block the rotation around the y-axis without block the rotation around the z-axis (because, of course, these enemies have to be able to flp in front of the player if he’s beside them)