How to assign a instantiated gameobject to other script of gameobject

You should take a bit more time on your question, be specific so people can answer you better.. Now, if you want to avoid gameObject.Find, you'll have to store the object when you instantiate it, wherever that is. You can store a reference to the script you want to add it to, if that is different than the script which instantiates the object. (you will probably still want to use "GameObject.Find" to initialize it though). For example:

 MyScript otherScript;

 void Start(){
   otherScript = GameObject.Find("NameOfObject").GetComponent<MyScript>();
 }

 void NewObject(){
   GameObject newObject = Instantiate(prefab, new Vector3(0, 0, 0), Quaternion.identity) as GameObject;
   otherScript.variableForObject = newObject;
 }

p.s. if my (or any) answer helps you, please remember to accept it, thanks..