Xamarin Android, SQLite and Batterydrain Warning

we are developing an App with Xamarin on Android, this App have a Chat System based on Push Notifications ( Pushwoosh ) and SQLite to store the Chat History. When a message arrive from another phone, the App store che Message into Database. The problem is when the app is in background, for some reason, when a message is recived, the Phone ( Asus Zenfone 2 ) give to us a warning message:

"This app cause battery drain, close it"

This message occur ONLY on ASUS Devices, it's ok on other Devices even with Clean Master installed. So i don't know how i can fix it. Any suggets?

This problem occur only when we recive a message and the App save it on Database when the app is in Background. Everything else works fine.

Thank you!