Can I pair smartphone over Bluetooth without a need to confirm this in user interface, accept to pair this devices. I use android studio. I don't need to exchange data over them, I need just pairing without any action. And then safely pair with smartphone over Bluetooth without any user's action?
Yes and no, but you shouldn't anyway.
The only way to do this in Android is by using the BLUETOOTH_PRIVILEGED permission, which, as you can see, is only granted to apps in /system/priv-app/ or apps signed by the platform key of the device.
So unless you have root and can move your app to /system/priv-app/, you can't do what you want. Even if you can do this, however, don't. It's not a good user experience when someone installs an app, only for it to move itself to the system partition and start pairing without any notification.