I've started this game 3 times today. And everytime I start it, it requires to install the game again....and again.....and again.....It's really making mad. I'm playing this game on a Macbook Pro 2012 model (Non-Retina). Was wondering if anyone else is having this problem?

Have you tried completely shutting down your Macbook, booting it back up and then launching Starcraft again?

Your best bet however, would be to ask on the Blizzard tech support forums as they might be more familiar with this problem.

What do you mean "requires to install the game again"? Recently, little patches have been coming out rapidly requiring a small period of time to wait before playing.

Open the dir where the game files are installed and run the fixer program within it. I'm not sure what its called but it usually fixes 90% of the problems you can have with sc2.