Note that interruptions are not the same thing as pushback. Focused Mind will not give any protection against the 'interruptions' caused by taking damage. Instead, the Restoration talent Healing Focus reduces the duration of such effects.
Patch changes
Patch 2.2.0 (25-Sep-2007): Effect increased from 15% to 30%.
Patch 2.1.2 (2007-06-19): Talent changed from giving a 15% chance to resist silence mechanics to a 15% reduction of the duration.