How to make a top-down camera but the player can't move it?

I'm making a game where the camera is set to be top-down, I've made the script to make it top-down but I don't want the player to move it when walking. Any idea on how to fix this?

[local RunService = game:GetService("RunService")   

local camera = workspace.CurrentCamera
local player = game.Players.LocalPlayer

local CAMERA_OFFSET = Vector3.new(-1,90,0)

camera.CameraType = Enum.CameraType.Scriptable

local function onRenderStep()
    if player.Character then
        local playerPosition = player.Character.HumanoidRootPart.Position
        local cameraPosition = playerPosition + CAMERA_OFFSET

        camera.CoordinateFrame = CFrame.new(cameraPosition, playerPosition)
    end
end

RunService:BindToRenderStep("Camera", Enum.RenderPriority.Camera.Value, onRenderStep)