Unity iPhone app size is too big

I built a unity game for iPhone which gave an app size of 288 MB. So tried with an empty unity project. Initially it generated app of size 33 MB. But after googling i could reduce it to 19.2 MB.

The changes i made: 1. Release build instead of debug build. 2. Target Device: only iPhone(in Unity settings). 3. Target Platform: armv7

The device log from unity showed:

Mono dependencies included in the build
mscorlib.dll

Textures 0.0 kb 0.0%
Meshes 0.0 kb 0.0%
Animations 0.0 kb 0.0%
Sounds 0.0 kb 0.0%
Shaders 0.0 kb 0.0%
Other Assets 0.0 kb 0.0%
Levels 6.7 kb 0.3%
Scripts 0.0 kb 0.0%
Included DLLs 2.4 mb 99.4%
File headers 8.0 kb 0.3%
Complete size 2.4 mb 100.0%

The package contents of my app has the unix executable with size 13.3 MB and Data 5.7 MB.

Is there any thing i must change in unity settings or Xcode to reduce the app size further? Please help me.