Found solution, added following lines in styles.xml file and it worked!!
<style name="AppTheme" parent="AppBaseTheme">
<item name="android:actionButtonStyle">@style/MyActionButtonStyle</item>
</style>
<style name="MyActionButtonStyle" parent="AppBaseTheme">
<item name="android:minWidth">20dip</item>
<item name="android:padding">0dip</item>
</style>