I'm sorry to say that this has issue was reported here in the forums in this thread in October. Since SimCity is no longer actively supported (the development team was dissolved a few years ago), it's unlikely you will see any patches or updates to the game. Community Manager
I had hope in the beginning of the year, but I fear that there just isn't going to be any official fix from either end. The best we could hope for would be an "accidental" fix if Apple updates the OS and something gets changed that makes it compatible with the game again. From what EA_Mage said, the issue appears to be with the internal Intel graphic card. (Although Aspyr said it was related to being a 32-bit game instead of a 64-bit game, but they were unable to "fix" it either).
The suggestions have been to try hooking an external monitor to force the MacBook to use a different graphic card; use a software program like gfxCardStatus to force it to use a non-Intel graphic card; install more memory (this worked for some - for a while - but the bigger the city, the more likely it was to crash). The one thing that probably works the best would be to run SimCity on a virtual Windows install or bootcamp drive. I know none of these is a great solution, but so far they seem to be the only options. I don't know anything about Macs, so I don't know if it's possible to do it, but you could attempt to force it to run in 32 bit mode to test the other theory.
I would suggest you add a reply of your own in the Mac crash thread, and subscribe so that you'll know if something changes. I wish I had a better answer for you. Good luck