The Mishnah states (Avos 1:12) that one should "love peace and pursue peace." The Maharal (Sefer Derech Chaim) explains that these are two separate concepts. "Loving peace" means ensuring that you don't get into altercations or fights with anyone. "Pursuing peace" means that if a fight breaks out, you should run to make peace. One must run to do this before the fight gets to big and the people involved get too distanced from each other.
Rav Menachem Mendel of Rimanov zy"a (Sefer Menachem Tzvio, Parshas Korach) writes similarly that when the pasuk says (Tehillim 34:15) to “turn away from evil, do good, seek peace and pursue it", it is indicating that shalom – which is listed as the last and most cumulative middah - is the most important of all middos. This is also why we end Shemonah Esrei with the tefillah of Sim Shalom, as we conclude with the most important thing. Therefore, although we are told to perform all mitzvos, we are only told to "pursue" peace. Since shalom is the most important middah, we are commanded to run after it. Furthermore, this indicates that one must pursue peace, in the sense that one must seek it out in order to spread it, as opposed to other mitzvos that one is only obligated to do if they come his way.
