Weird movements of robots???

Simple,I got a robot from assets store which has no scripts attached to it.So i wanted to make it as an Enemy.First I wrote a script to follow player.It works simply it follow my player from long distance.But it cant rotate.This is my script.. public float speed; private Transform target; // this for initialization void Start() { target = GameObject.FindGameObjectWithTag("Player").GetComponent(); }

 // Update is called once per frame
 void Update()
 {
     transform.LookAt(target);
     Vector3 relativePos = target.position - transform.position;
     transform.position = Vector2.MoveTowards(transform.position, target.position, speed * Time.deltaTime);
     transform.position = Vector3.MoveTowards(transform.position, target.position, speed * Time.deltaTime);
     transform.LookAt(target.position); //With this line the obj rotate


 }

I added didnt add rigidbody for robots.Im very new,so please help!