How to click a UI button without activating mouse

I made a UI button to select a block and my mouse click spawns a block, but I don't want it spawn a block when I'm about to press a button, and it does anyway..

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 
 public class GameData : MonoBehaviour {
     public Text crateButton;
     public Text crateButtonP;
     public Text metalButton;
     public Text metalButtonP;
     public GameObject crate;
     public GameObject crateP;
     public GameObject metal;
     public GameObject metalP;
     float blockType = 2;
     float crateAmount = 100;
     float blockAmount = 100;
     float crateAmountP = 100;
     float blockAmountP = 100;
     void Start (){
         crateButton.text = crateAmount.ToString ();
         metalButton.text = blockAmount.ToString ();
         crateButtonP.text = crateAmountP.ToString ();
         metalButtonP.text = blockAmountP.ToString ();
     }
     
     void Update () {
 
         if (Input.GetMouseButtonDown(0)) {
             Vector2 position = Camera.main.ScreenToWorldPoint(Input.mousePosition);
                 if (blockType == 1){
                         if (crateAmount >= 1){
                     Instantiate (crate, position, Quaternion.identity);
                         crateAmount = crateAmount - 1;
                             crateButton.text = crateAmount.ToString ();
                         }
                 }
                 if (blockType == 2){
                         if (blockAmount >= 1){
                     Instantiate (metal, position, Quaternion.identity);
                         blockAmount = blockAmount - 1;
                             metalButton.text = blockAmount.ToString ();
                         }
                 }
                     if (blockType == 3){
                         if (crateAmountP >= 1){
                             Instantiate (crateP, position, Quaternion.identity);
                             crateAmountP = crateAmountP - 1;
                             crateButtonP.text = crateAmountP.ToString ();
                         }
                 }
                     if (blockType == 4){
                         if (blockAmountP >= 1){
                             Instantiate (metalP, position, Quaternion.identity);
                             blockAmountP = blockAmountP - 1;
                             metalButtonP.text = blockAmountP.ToString ();
                 }
             }
         }
     }
     public void CreateBox (){
         blockType = 1;
     }
     public void CreateMetal (){
         blockType = 2;
     }
     public void CreateBoxP (){
         blockType = 3;
     }
     public void CreateMetalP (){
         blockType = 4;
     }
 }