Can't really grasp how to keep my player level on X and Z while using LookRotation

Here's my code, I'm pretty new to Quaternions and can't quite figure out what to alter here to keep my player rotating on the Y, but not X or Z.

Quaternion enemyDirection = Quaternion.LookRotation(targetPosition - transform.position); transform.rotation = Quaternion.Slerp(transform.rotation, enemyDirection, Time.deltaTime * 20f);

Thanks!