The 40-year-old sustained the injury during pre-season and tweaked the problem again carrying travel bags.
As a result, he made the choice to rule himself out of the entire campaign.
Bryant told reporters: "You can control what you can control. He did everything to get back and play at a high level. From that standpoint he should be able to sleep at night.
"I know I would. I can only think about that in my situation; I just tried to do everything possible to be ready, and if it wasn't in the cards, if I couldn't get back to being at that level, you just have to accept it and when you lay your head down you know that you did absolutely everything possible."
Nash played just 15 games for the Lakers in the 2013-14 season due to nerve root irritation.