"हमें संतरे नहीं पसंद।"

Translation: We do not like oranges.

[Nikole42]

is है wrong here or is it omitted for ease of speech?

[zeebo7]

It is often omitted when the sentence is a negation, but there is nothing wrong with including it. Fun fact: aparently the historical word for no was न, and नहीं was a contraction of न + हैं.