I don't recall them having specific comments.
I know Biggie heard it but never said anything specific about the album, though he didn't really catch any disses on it other than just in the intro. He did acknowledge the album's success (not by name though) in one of the last interviews he did where they are outside in some fenced basketball court or something where he makes a comment to the effect of Pac "still running the radio" or something.
Jay-Z's only comment that I recall was on Wanted Dead or Alive (or whatever the song was called). On the Makaveli intro, there was the mention of the "Hawaiian Sophie" track, and on the Jay-Z song in discussion, he says something about Pac must having been on his "dick for a long time" if he knew about that since it was an older and lesser known video from the early 1990s. That aside, Jay-Z never really said much else.
Mobb Deep responded back on Drop a Gem on 'Em and a couple of tracks that I can't remember.