"The striving for peace and the efforts to achieve it are clashing with the fact that there are so many armed conflicts in the world today. This is sort a of third world war being waged in parts," he said during a service at Kosevo stadium before 70,000 believers.
"There are some who are causing such a climate, who are causing conflicts between cultures and civilisations and who are conceiving wars to sell weapons."
The war means children, women and elderly in refugee camps, leaving home, destruction of houses, schools, homes for the elderly and, first and foremost, destroyed lives, the Holy Father said. "You know that very well... How much destruction, how much suffering, how much pain. In this city, God's people is crying out: No more war."
The pope was on a one-day state and pastoral visit to Bosnia and Herzegovina, which lost more than 100,000 lives in the 1992-95 war. Sarajevo was under siege by Bosnian Serb forces from April 1992 to February 1996. About 15,000 of its inhabitants were killed.
Pope Francis called on Croats, Bosniaks and Serbs in Bosnia to pursue harmony and peace, saying it was "a job done every day, step by step... Peace is an act of justice which is applied, lived. A person, a people that I saw as an enemy has my face, my heart, my soul. True justice would be to do onto that person and people everything I wish were done onto me and my people."
The pope said "the creation of peace is an art, it demands passion, patience, experience, consistency... Blessed are those who sow peace through everyday work, gestures of service, brotherhood, mercy."
"We pray to God to have a simple heart, full of patience and advocacy for justice, that we advocate and create peace and not war and disharmony. It is the only way that makes us happy and blessed," the Holy Father said.