high horse

climb/get on your high horse (if someone gets on their high horse about a subject, they become angry about it and start criticizing other people as if they are better or more clever than them) — произносить обличительные тирады; заноситься; вести себя высокомерно; задаваться; важничать; понты раскидывать (контекст)

Example: It's no good getting on your high horse about single parents. You can't force people to get married.

come/get (down) off your high horse (to stop talking as if you were better or more clever than other people)

Example: It's time you came down off your high horse and admitted you might have made a mistake. (CIDI)

high horse means something that denotes much pride. High horse has an informal use in English language. It is a mood or attitude that is stubborn or arrogant. A person who has such an attitude considers his own self superior to others and behaves arrogantly or rudely. He looks upon others with contempt.

For example: Get down off your high horse and accept your mistake. Here, a person is being told to stop behaving arrogantly. A person considered to be on his high horse offends people around him by his behaviour. High horse could mean haughty attitude or temper, self-importance, self-love, smugness, superciliousness or vanity, conceitedness or contemptuousness. (blurtit.com)