Kalila and Demna is a collection of fables, and it has a significant influence on Eastern culture, just as Aesop's fables probably does on Western culture. In Kalila, there's a story about a difficult, unmanageable donkey that's ready to kick and hurt anyone. Occasionally, the donkey would throw off the person and the load on it. People, angry at the scary donkey, would hit the saddle in revenge because they can't really hit the donkey. From this arose an expression that translates as
To spare the donkey, but to be a lion to the saddle.
In other words, to be brave when attacking the weak irrelevant saddle, but to avoid addressing the real intimidating source of trouble. I would use this expression, for example, whenever Mom and Dad have a fight, and then Dad, instead of lashing out at powerful Mom, lashes out at me.
A close English expression that I'm aware of is bark up the wrong tree but the problem with it is that it doesn't suggest cowardice in the person barking up the wrong tree as does the Arabic expression.