The letter is the latest chapter in an unprecedented public debate over whether to attack Iran to prevent it from developing a nuclear weapon.
Netanyahu and Defense Minister Ehud Barak are believed to favor such a strike, while top former defense officials oppose it. Recent comments attributed to Barak have raised speculation that Israel might be preparing to attack.
In the letter, the authors threaten to take legal action if Netanyahu doesn't commit by the end of the week to a vote in his 30-member Cabinet.
Among the signatories is acclaimed author Amos Oz.