First don't ever say this is what my manager told me to do to his/her boss, accept critics and say that you will improve. Then talk to your manager and explain

First don't ever say this is what my manager told me to do to his/her boss, accept critics and say that you will improve. Then talk to your manager and explain the situation, you don't know their relationship and if the critics are towards you or really are a way to criticize your manager. Besides that work at your best and speak a lot to your manager for feedback