Bush needs to stop attacking Trump in an effort to kickstart his campaign. Clearly Bush is struggling and people don't want him to be the nominee. Trying to attack and take down someone else to make yourself look better is not a good strategy. Bush is coming off as weak.
Jeb Bush's attacks on Donald Trump have not been very effective and have only served to make Bush look silly and ineffective. When candidates attack each other it is not helpful to the images of either the attacker or the person being attacked. Bush would be better off to point out inconsistencies in Trump's platform instead of attacking him.
Bush should not stop attacking Trump because it is fair to criticize opponents. So long as what any candidate says about another is true, a candidate has the right to say it, even if it seems like an attack. If Trump (or any political candidate) does not want to be attacked by criticism from other candidates, he should behave in a way where others wouldn't be able to attack him.
I do not consider myself a Republican, but if I were to choose a GOP candidate, my first choice would be Jeb Bush, and my last choice would be Donald Trump. I like that Bush is standing up to Trump and calling him out on his being ignorant. I hope Bush keeps this up, and makes a splash.