Star Trek: Insurrection(1998)

Plot : As Jean Luc Picard attends festivities onboard the Enterprise welcoming a new race to the Federation. He receives an urgent call from Admiral Dougherty about Data, that was sent on an observation mission of the Ba'Ku race. The Federation has installed there a hidden outpost and the So'Na race is there too. Data has gone out of control and reveals the federation outpost to the natives. Picard and his senior officers get on the planet to discuss with them to surrender the Federation personnel.

He is welcomed by the (extremely) peaceful Ba'Ku that are represented by Anji and Sojef, that explain the history and philosophy of their people. They have settled on this planet generations ago and have benefited from a local radiation extending their life greatly.
Picard is pushed by Dougherty to leave the planet to let the "observation" mission without interference. Picard smells deception and will have to disobey orders to defend one of the Federation's basic principles.
I know most people don't like this movie and rank it low among the Star trek movies. Of course there's not much action and fights. The new characters are either very boring or too obviously "evil".

But the main point here is to defend the "prime directive" (= not to interfere in the development of a civilization that is inferior in technology. There is not much else here than a deep analysis of what the Federation is and when it must or not intervene. So there's a light love story wit Picard and Anij, Data befriends a kid in his discovery of humanity's young age behavior.

After many movies about the Klingons, Romulans ... I found it fresh to have two (?) new races with different histories and ways of life. And having the movie centered on the "prime directive", and how a cunning race can twist it (after all, the Ba'Ku are not really "natives" of the planet and shouldn't be protected by the prime directive), and how one superior officer, if misleaded, can lead to eradication of hundreds of people.