Any way to stop iCal launching automatically each time an event is synced with iCloud?

iCloud is now syncing properly among my devices, but now each time I create, delete or modify an event on my iPhone, iCal will automatically LAUNCH on my Macbook Pro. Furthermore, since I don't actually use iCal - but rather Fantastical - each time I create a new event on my Mac, it will launch iCal to sync with iCloud.

Is there a way to prevent this from happening? This never happened with MobileMe syncing.