Player Rotation Around Mouse

Hey guys, i'm having some problems with my player rotation around the mouse only using horizontal motion. I would like the player to always be pointing towards the mouse no matter the position on the screen although, the player is only rotation to the mouse according to the coordinates on the screen and not in the game world.

The player is also doing weird things like moving on its own. I have been working on this problem for days now and i just can't seem to crack it. Oh also, just in case this is relevant, the game is isometric. I thought that maybe this would be the cause but i just can't see at to why it would be.

Here is the code i am using:

 void Update () {
 
         Vector3 lookDirection = (new Vector3(Input.mousePosition.x, 0, Input.mousePosition.z));
         lookDirection.y = 0;
 
         Debug.Log(lookDirection);
 
         transform.LookAt(Camera.main.ScreenToWorldPoint(lookDirection));
         
 
     }

Thank you very much in advance!