How to show the accreditation of a university abroad
Various countries have different accrediting bodies. Wikipedia has a nice overview.

From what you've written, it seems like they are looking for some information about what body (usually a private accrediting agency or a government ministry of education) your undergraduate institution is accredited by. To use a school near me as an example, I might say something like:


  Brooklyn College is accredited by the Middle States Commission on Higher Education, as stated here.  You can see Brooklyn College listed on the accrediting body's website, here.


In your case, you can point them to this page, which shows that the university is accredited by the Ministry of Science, Research and Technology of Iran (which is the government body that is responsible for accreditation of institutes of higher education in Iran).