discourage

(verb) try to prevent; show opposition to. Synonyms: deter. Example: "We should discourage this practice among our youth."

(verb) deprive of courage or hope; take away hope from; cause to feel discouraged.

(verb) admonish or counsel in terms of someone's behavior. Synonyms: warn, admonish, monish. Examples: "I warned him not to go too far." "I warn you against false assumptions." "She warned him to be quiet."