Editing 2 position axes

So, I'm trying to control a camera. The camera is supposed to follow the player and move up and down fluidly in places that I will set a Trigger in. The x axis is determined like this:

 float playerX = player.transform.position.x;
         float cameraX = playerX + 20;

The Z axis is simply:

 player.transform.position.z

Now, the Y axis is not supposed to be edited by the coding in any way, since it is controlled by a mecanim animation. Now comes the problem:

I can't just plug in the two values, since Unity then calls me out because transform.position.x and z are not variables and cannot be edited.

But if I use a Vector3 like this:

 float playerX = player.transform.position.x;
         float cameraX = playerX + 20;
         Vector3 cameraTransform = transform.position;
         cameraTransform.x = cameraX;
         cameraTransform.z = player.transform.position.z;
         transform.position = cameraTransform;

The Vector3.y always overwrites the animation, so it might just not play at all. How can I leave the Y axis alone?

I appreciate any help.