Mac OS X 10.7 and later do not support Rosetta, the application to allow pre Intel Mac (2006) installed applications to run. This link offers software for every Mac operating system for your camera:
http://www.usa.canon.com/cusa/consumer/products/cameras/slr_cameras/eos_rebel_t3 i_18_55mm_is_ii_lens_kit#DriversAndSoftware
Canon drivers:
Canon Inkjet Printer Drivers v2.12 for OS X
Support the printers here:
OS X: Printer and scanner software available for download
when combined with the printer drivers on Canon's website on Mac OS X 10.6 or later.
This tip may offer help if you are running into other compatibility issues with Mac OS X 10.7 or later:
https://discussions.apple.com/docs/DOC-6271
Go to Apple menu -> About This Mac to find your operating system, and MacBook processor.