Assuming your application is complete, it likely means your GPA and/or MCAT are a bit too low but not quite low enough to flat-out reject you. This is actually better than a rejection because it means the school likes aspects of your application enough to keep you in the "maybe" pile. My best suggestion if it's a GPA issue is to update them with any summer grades you might have once they're available and/or to update them with this fall's grades. If it's an MCAT issue, you need to take the MCAT again and update them with the new score whenever it becomes available. Aside from that, just keep them updated on any additional activities (research, publications, shadowing, etc) that you have going on (though, if it's a numbers issue I'd personally forgo extracurriculars in lieu of better class/test performance).
Basically, the ball is in your court. If you aren't proactive and show the school that you're doing stuff to make yourself a better applicant and alleviate their concerns, you can consider this a rejection. If you're proactive and show the school you mean business, your chances of an interview will definitely be greater.
