Import Users from D6 to D7 without directly accessing database I have to import users from a drupal 6 site to a drupal 7 one. I'd use https://www.drupal.org/project/migrate_d2d but i have several limitations on what i can do on the databases: 


I can't access the drupal 6 DB from the drupal 7 installation 
I don't have ssh access on the D7 server, i can interact with the database only from phpmyadmin
I can't create new databases on the D7 DB (i can create new tables though), and i can import sql files only to a maximum of 10MB. I can't upload a file on the server then import it from local either.
I have no limitations on the D6 database


In addition, user roles are different from the 2 sites so i need to map them before importing.
I think the best solution is to export data from the D6 site in some format and the import it on the D7 site but i don't know how to do it
Views data export module is perfectly capable of exporting your users to CSV file. You would use Views to define what you want to have exported, so you can export anything. You can also use Views GUI to define mappings, if you want. It is a powerful toolset, and VDO uses all that power.

When you will have your users in CSV, you can use User Import to import them. Pretty obvious, isn't it? For mapping, User Import can


  
  Match CSV columns to account and profile fields
  


So if you didn't manage to do it on the Views level, you can always edit CSV when you'll have it locally, or try to do it on import... So many options, I'm sure at least one will work.

Last but not least, make sure your users will get mails with "new password required" explanation, as D6 and D7 stores passwords in incompatible ways.