The children of Israel didn't strike them, because the princes of the congregation had sworn to them by Yahweh, the God of Israel. All the congregation murmured against the princes.
"’This account,’ as O. v. Gerlach says, ’is a warning to the Church of God of all ages against the cunning and dissimulation of the world, which often seeks for a peaceable recognition on the part of the kingdom of God, and even for a reception into it, whenever it may be its advantage to do so.’" [Note: Keil and Delitzsch, p. 95.] 