Cordova + Vue - Error Block-scoped declarations

Hi guys. I use Framework7 with Vue. After check dev compiled app for android on Android device with 6 version i have an error:
Error: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
How can i solve this problem? I use google and i read about ES6 feautures not supported on Android 6 API version.

Add babel/buble to webpack/gulp