Hi shaha26,
Presently, there is no Microsoft Project for Mac version, I regret for it.
After searching, I found an article discussing this feature on Mac. I think this can be the reference for you:
Project Online: How do I use my Apple Mac?
http://blogs.technet.com/b/projectsupport/archive/2013/05/21/project-online-how-do-i-use-my-apple-mac.aspx
Thanks,
Elaine Hao