If you're trying to make a teleport Gui, you should use a LocalScript. When you teleport the Player you should move their HumanoidRootPart using CFrame. MoveTo is to actually walk a player or NPC to the desired part, which is probably what you don't want. Also, when you try to move the player, you used Player1 which will only try to find Player1 instead of whoever clicks on the button. Here is the fixed script.
function teleport()
game.Players.LocalPlayer.Character.HumanoidRootPart.CFrame = CFrame.new(workspace.tp1.Position)
end
script.Parent.MouseButton1Click:connect(teleport)
Once again, you should use a LocalScript, not a normal Server Script.