This was from The Twilight Zone, the series that started in 1985. The episode was A Small Talent For War, aired in January 1986, and is one of my favorites.
From the plot synopsis on Wikipedia (https://en.m.wikipedia.org/wiki/A_Small_Talent_for_War):
An ambassador (John Glover) from an alien race arrives, claiming that his race had genetically engineered the people of Earth. He tells the quarrelsome members of the United Nations Security Council that his race is displeased over Earth's "small talent for war", having failed to produce the potential that the aliens had nurtured. When the ambassador announces that his fleet will destroy all life on Earth, the Security Council pleads for and is granted a 24-hour reprieve to prove Earth's worth. With the survival of humanity at stake, the Security Council and the General Assembly negotiate an accord for lasting global peace and present it to the alien ambassador.
The global peace agreement brings great humour to the emissary. The aliens were, in fact, seeking a greater talent for war, as they had genetically seeded thousands of planets to breed warriors to fight for them across the galaxy