If you believe your Galaxy S7 (S7 Edge, S6, S5, Note 5, Note 4) vibrates with no reason when picking it up, the Smart Alert feature is enabled and you have some unread notifications. To stop Galaxy S7 from vibrating when picking it up, do as follows:
1. Open the Settings application on your Galaxy device and go to the Device tab
2. Tap to open the Advanced Features option
3. Now find the Smart Alert option, open it and make sure to toggle it off. When the Smart Alert is enabled, your device will vibrate as soon as picking it up, if you have new message or missed call.