Under the apple review guidelines section

5.2.3 Audio/Video Downloading: Apps should not facilitate illegal file sharing or include the ability to save, convert, or download media from third party sources (e.g. Apple Music, YouTube, SoundCloud, Vimeo, etc.) without explicit authorization from those sources. Streaming of audio/video content may also violate Terms of Use, so be sure to check before your app accesses those services. Documentation must be provided upon request.

Following instruction would be helpful to use iTunes song preview:
– iTunes song previews can only be used to promote the track. They cannot be used for entertainment independent of that purpose, or as the main focus of an app.
– iTunes song previews can only be streamed, they may not be downloaded, saved, cached or synchronized with video.
– iTunes song previews must be used with an approved “Download on iTunes” badge; they may not be used in any other way.
– The link associated with the badge needs to point to the track the sample came from, or at least the same album or artist.
– Anytime an iTunes song preview is used, the text “provided courtesy of iTunes” must also exist somewhere nearby.
– Previews can only be used from within countries that also have an iTunes Music Store. Access from outside the intended countries will result in an error and song previews may not play.