Does Iran's sanction play a pivotal role in rejecting papers from a journal? After 1.5 years of hard work on a project,  my former supervisor sent our paper to a journal. After about 10 hours, they sent the following response:


  After careful internal editorial consideration of your manuscript, we regret to inform you that we have decided not to pursue further peer review. We receive an extensive number of quality manuscripts each week and must make difficult decisions regarding which to progress in the peer-review process.  Generally, no editorial comments are available for papers that are not sent for external peer review.


My professor said that these kinds of things are happening frequently nowadays. 

I supposed that is because of sanction (we are Iranian). Is this likely to be the case? 

We are ordinary people with an academic background who caught up in tensions between countries and do not know what to do. I am going to pursue my Ph.D. in a university in Europe, Australia or New Zealand. In the admission board, they may look at my published papers sections on my CV, and with these kinds of behavior from international journals, I do not know what to do.
Speaking as an associate editor of a US-based journal that receives many international submissions, I can tell you that:


There are absolutely no guidelines or even informal suggestions that any paper should be handled differently based on the nationality of the authors or their institutions.
I have never heard of anyone making editorial decisions on such a basis or suggesting that they should.
In my own opinion, which I believe is shared by most or all of the other editors, to do #1 or #2 would be highly unethical.


I couldn't even tell you, without going and checking one by one, whether any of the papers I have handled recently had Iranian authors, because it absolutely doesn't matter.

Edit: following up on @Allure's answer below (which links to some older information), it seems there is a very slim and rare legal basis that would hypothetically prevent some editors from handling some manuscripts from Iran and other countries under US sanctions.  It definitely does not apply to the case discussed here, and would not be grounds for rejection since practically any major journal will have editors who are not bound by this restriction.  The most clear and recent explanation I could find is here.  The current rules are the result of a 2004 lawsuit that overturned much more restrictive rules in place back then.

Further edit: It seems that there is a recent instance of misinterpretation of the laws mentioned above, which led to rejection of a manuscript purely on the grounds of one author having an Iranian affiliation.  Eventually this was resolved and the rejection decision was reversed.  Note that in that case, the authors were specifically informed that the decision was based on US sanctions (albeit misinterpreted), and the decision was not made by or communicated by the journal editors.