How to set up limits for player movement (2d)

Hi, I´m trying to set limits for player movement, but since I´m not using transform.positions I was unable to do it. Anyone knows how it can be done? This is the code I´m working with.

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour {
		
		public Vector2 speed = new Vector2(50, 50);
		
		private Vector2 movement;

		public int dir = -1;
	
		private float cmovforce = -5;

		
	void Update() {

	
		bool shoot = Input.GetButtonDown ("Fire1");
		
	
		//Ship Mov
		if (Input.GetKeyDown(KeyCode.LeftArrow) || Input.GetKeyDown(KeyCode.A))
		{
			dir = 1;
			
		}
		
		else if (Input.GetKeyDown(KeyCode.RightArrow) || Input.GetKeyDown(KeyCode.D))
		{
			dir = 1;
		}
		
		if (transform.position.x <= -8)
		{
			dir = 0;
		}
		
		
		Vector3 temp = transform.localScale;
		temp.x = dir;
		transform.localScale = temp;
		
		float cmov = cmovforce * dir;
		
		if (shoot) {
			WeaponScriptPlayer weapon = GetComponent<WeaponScriptPlayer> ();
			if (weapon != null) {

				weapon.Attack (false);
			}
		}

		{
		
		float inputX = Input.GetAxis("Horizontal");
			 
		float inputY = Input.GetAxis("Vertical");

		
		// 4 - Movement per direction
			movement = new Vector2((speed.x * inputX) + cmov, speed.y * inputY);
				/*(
			speed.x * inputX,
			speed.y * inputY);*/

		
	}
	}
			
		


		void FixedUpdate()
		{
			
			GetComponent<Rigidbody2D>().velocity = movement;
		}

	void OnCollisionEnter2D(Collision2D collision)
	{
		bool damagePlayer = false;
		
		// Collision with enemy
		AtAtScript enemy = collision.gameObject.GetComponent<AtAtScript>();
		if (enemy != null)
		/*{
			// Kill the enemy
			HealthScript enemyHealth = enemy.GetComponent<HealthScript>();
			if (enemyHealth != null) enemyHealth.Damage(enemyHealth.hp);
			
			damagePlayer = true;
		}*/
		
		// Damage the player
		if (damagePlayer)
		{
			HealthScript playerHealth = this.GetComponent<HealthScript>();
			if (playerHealth != null) playerHealth.Damage(20);
		}
	}

	void OnDestroy()
	{
		
		transform.parent.gameObject.AddComponent<GameOverScript>();
	}
}

You can do it in the following way. Hope I understood your question right.

You can clamp the position. Simple Example:

    var pos = transform.position;
    pos.x =  Mathf.Clamp(transform.position.x, 0.0f , 0.0f);
    transform.position = pos;