Enemy is not stopping following the player

hi I have edited your script a bit try using it

 var target : Transform;
 var moveSpeed = 0;
 var rotationSpeed = 3;
 var player : Transform;
 var distance:flaot = 5.8;
 var distanceAttack:float = 2.6;
 var myTransform : Transform;
 
 function Awake() {
 myTransform = transform;
 }
 
 function Start() {
 animation.Play("idle");
 target = GameObject.FindWithTag("Player").transform;
 }
 
 function Update () {
 if(Vector3.Distance(transform.position, player.position) < distance){
 if(Vector3.Distance(transform.position, player.position) >distanceAttack){
 moveSpeed = 2;
 animation.Play("walk");
 myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
 Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
 myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
 }
 
 if(Vector3.Distance(transform.position, player.position) < distanceAttack){
 moveSpeed = 0;
 animation.Play("attack");
 }
 }
 else{
 moveSpeed = 0;
 animation.CrossFade("idle");
 }
 }