The first thing for you to consider is your English language proficiency. Every American school has a minimum TOEFL (Test of English as a Foreign Language) requirement for foreign applicants.
Secondly, your chances depend on more than just your grades and GRE scores. However, given the uphill battle you will face as an international applicant, I think it's safe to say that your grades will keep you out of the top schools since foreign nationals with better credentials routinely get rejected from most programs.
That said, you might have a reasonable chance at some of the lower tier schools if you have excellent letters of reference and a great deal of research experience, but keep in mind that a 2.5 GPA is farily low and most American students with similar grades have a hard time getting accepted anywhere.
It might be in your best interest to get a master's degree (or at least some additional research experience) in your country of origin before wasting your money on a bunch of applications since the process can cost you over 1000 dollars just to be considered. This way, you will get a chance to get better grades and maybe even a paper before coming here to get your PhD.
Nobody will care about your 2.5 GPA if you do well in a master's program... which you should have no trouble doing with a 910 on the physics GRE.
Hope this helps