"A bird in hand is worth two in the bush"
You say you got a call from your preferred option, but that doesn't guarantee that you will land an offer with them.
On the other hand, you already have this Internship, and depending on what you mean by accepting the Internship seems that you have already committed to that offer. If you have already formalized the internship (signing some contract or similar), then backing off now would be unprofessional from your part.
However, if you haven't formalized the internship yet, then you could explore the other option and perhaps work it into an offer in some time. Nothing is guaranteed, so have that in mind when deciding what you want to seek, as well as the relevance of the job to your desired career path.
Anyways, seems that you don't have much time to sort this out, so I suggest you get to it ASAP.