They had high hopes for the protests that they fueled. They thought they would last longer and become more violent.

The crackdown by Iran government on Jan 8th quelled the protests quickly and succinctly. 

They didn't have the US military assets in place in the region before that and then decided without having the protestors fulfill the boots on the ground, it would be impossible to overthrow the regime with airstrikes alone.

In fact BiBi likely asked Trump to not attack Iran since without a high chance of overthrowing the regime, Israel would take on another barrage of missiles from Iran and they didn't like how the Iron Dome faired the last time Iran attacked.