I need my AI to attack any object who is tagged with a specific tag like let's say "enemies".Can someone help me?.I tryed everything and nothing seems to work.

Something like this ..

Make sure your player has been tagged as Player, then drag it into the Target in the Inspector window

Hope this helps ..

 #pragma strict
 
 var Target : Transform; // Drag your player to attack in here
 var distance = 30; // Distance
 var lookAtDistance = 20; // Distance to keep looking at the player
 var attackRange = 10; // Range to start the attack
 var attackSpeed = 3.0; // Speed to attack player
 var dampingLook = 6.0; // Slow the rotation
    
 function Awake()
 {
  if(!Target)
  {
  Target = GameObject.FindWithTag("Player").transform; 
  }
 }
 
 function Update()
 {
  distance = Vector3.Distance(Target.position, transform.position);
  
  if(canAtackTarget())
  {
  var targetRotation = Quaternion.LookRotation(Target.position - transform.position, Vector3.up);
  transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, Time.deltaTime * dampingLook);
  }
 
  
  if(canAtackTarget() && !attackRange){
  attack();
  }
 }
 
 function canAtackTarget()
 {
  if(distance > lookAtDistance)
  {
  renderer.material.color = Color.green;
  print("Out of range");
  return false;
  }
  
  if(distance < attackRange)
  {
  renderer.material.color = Color.red;
  print("Attacking");
  attack();
  return true;
  }
  
  var seeYou : RaycastHit;
  
 // Check to see if there is anything inbetween enemy and player
  if(Physics.Linecast(transform.position, Target.position, seeYou))
  {
  if(seeYou.collider.gameObject.tag != "Player")
  {
  print("Can not see you " + seeYou.collider.gameObject.name + " in the way");
  renderer.material.color = Color.green;
  return false;
  }
  else
  {
 //Player ditected
  renderer.material.color = Color.yellow;
  return true;
  }
  }
  return true;
 }
 
 function lookAt()
 {
 var rotation = Quaternion.LookRotation(Target.position - transform.position, Vector3.up);
 transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * dampingLook);
 }
 
 function attack()
 {
 // The Vector3 0.2 stops the object going into the floor
     transform.Translate(Vector3(0, 0.2, 1) * attackSpeed *Time.deltaTime);
 }