This is a section where we have a hint of lead playing amidst all the rhythm. It adds a tasty flavor to the tune.
There's a little bit of string skipping in this as you'll see during the first few notes. Also, observe how the very first 3 notes are all D notes. You'll play the open D string, then the 12th fret which is also a D note, then the 15th fret B string, which is also a D note. So we get a good use of octaves in this riff.
Lastly, make sure you use alternate picking exclusively through this passage.