A cease fire (or a truce) is a temporary lull or official halt during a war in which both sides agree to suspend further offensive actions against each other.
In 2152, Andorian Imperial Guard Commander Thy'lek Shran then told the Vulcan High Command that he was willing negotiate a ceasefire on Weytahn. His one condition was to have the Enterprise's captain, Jonathan Archer negotiate it with Ambassador Soval. (ENT episode: "Cease Fire")
During the Battle of the Binary Stars, Starfleet Admiral Brett Anderson of the USS Europa then proposed a cease fire to the Sarcophagus's commander, T'Kuvma and his Klingon forces. At first, T'Kuvma accepted the cease fire, but used as opportunity to demonstrate a cleave ship's cloaking device. The cleave ship rammed into the Europa and both were then destroyed. Following the end of the Federation-Klingon War of 2256-57, a cease fire was established between the Federation and Klingon Empire to end the war. (DSC episodes: "Battle at the Binary Stars", "Will You Take My Hand?", bonus scene")
In 2267, shortly after the Organians halted an impending war between the Federation and the Klingon Empire, in TOS episode & Star Trek 2 novelization: Errand of Mercy, a cease fire existed prior to the official signing of the Organian Peace Treaty. During the cease fire, a state of war continued to exist. On the planet Angrena, landing parties from both sides shot and killed each other. Captain James T. Kirk and Klingon Commander Kring agreed that if opposing starships fired upon each other, however, then the cease fire would end. As a sign of good faith, Kirk allowed Kring and his crew to depart in peace. Kirk then found himself on trial, as a Starfleet directive technically forbade him from releasing prisoners of war. (TOS - Star Trek: The Manga - Uchu comic: "Art of War")
In 2373, Gowron ordered a ceasefire during the Federation-Klingon War of 2372-2373 when a Changeling posing as Martok was exposed and killed. The ceasefire briefly broke down when Ajilon Prime was attacked in the Battle of Ajilon Prime but it was later reinstated. (DS9 episodes: "Apocalypse Rising", "Nor the Battle to the Strong")
In 2233, the Romulan mining ship Narada's second-in-command, Ayel, then asked the USS Kelvin's captain, Richard Robau to come aboard the Narada to discuss a cease fire with Captain Nero. (TOS movie, novelization & comic adaptation: Star Trek)