Follow AI goes up when it gets near me!

Hello! I am not too good at scripting, so if someone could tell me how to alter this script so the AI stays on the ground that would be awesome!

I know it has something to do with not rotating the Y axis but that is as far as I can figure out. Here's what I'm working with

  private var Player : Transform; //This get the Player Transform
     var Speed : float = 1; //This is the Enemy Speed
     var Distance : float = 15; //The Distance before he can see the player
     var Smooth : float = 2; //This is how fast the Enemy Rotate
     
     function Awake ()
     {
     Player = GameObject.FindGameObjectWithTag("Player").transform;
     //Set our private var Player to find a GameObject with tag "Player"
     }
     
     function Update () 
     {
     //Check the Distance
     if (Vector3.Distance(Player.position,transform.position) <= Distance)
     {
     renderer.material.color = Color.red; //If he see you his color change to Red
     transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(Player.position - transform.position), Time.deltaTime * Smooth);
     //Look At the Player    
     transform.position = Vector3.MoveTowards(transform.position, Player.position, Speed * Time.deltaTime);
     //Move Towards the Player
     }    
     else    
     {
      renderer.material.color = Color.green; //if he don't see you his color change to green
     }    
 }