WordPress allows user to upload various types of files using the media upload functionality. There is no visible way for restricting users from uploading files of one or more file types. However you can do this using filters. So, I decided to create a plugin which will provide user interface for selecting which files the users will be able to upload. WP Upload Restriction is the plugin which allows administrators to choose the files types and restricts users from uploading files other than the selected types. It’s a very simple, easy-to-use, yet powerful plugin.
Currently the file type restriction is applied to all users except administrators. In next release(s) role wise restrictions will be added.
To grab a copy of this plugin visit this link https://wordpress.org/plugins/wp-upload-restriction/.