How to Stop Transform.Position in X-axis = 0 ?

Excuse me, anyone know how to stop my gameObject Transform.Position if x-axis = 0 ?
On this case, i’ll make AR with Vuforia ImageTarget, and i want to stop this transform.position in the center of imageTargets…

This is my sample code i used :

    private TrackableBehaviour mTrackableBehaviour;
	private bool isRendered = false;
	private GameObject Mobil;
    
    void Start()
    {
        Mobil = GameObject.Find("Mobil");
		
		mTrackableBehaviour = GetComponent<TrackableBehaviour>();
        if (mTrackableBehaviour)
        {
            mTrackableBehaviour.RegisterTrackableEventHandler(this);
        }
		
		OnTrackingLost();
    }
	
	void Update()
	{
		if (isRendered && Mobil.transform.position.x < 140){
		Mobil.transform.position += Mobil.transform.forward * 10.0f * Time.deltaTime;
		}
	}

if transform.position.x > target.position.x
transform.position.x -= Time.deltaTime * speed

 if transform.position.x < target.position.x
 transform.position.x += Time.deltaTime * speed

This will cause jittering, but you get the idea.