@Shruti_Sawant I think to make restrictions as you want it's still impossible,
but there is a possible way, that is by using the Sign-In System in the app that you created.
So by using the Sign-in System you can give permission to enter the application only for certain people that you have registered.
Useful Links:
🔥 Register and Login using Firebase Authentication for your app
🔥"Subvert" Firebase Authentication or (One Authenticated User for Multiple User Logins)
(GeeksForGeeks)
How to Make a Login and Sign Up Application in MIT App Inventor using Firebase?