The first American pope, who has drawn the ire of President Donald Trump after becoming more outspoken in recent weeks, also decried what he called the "colonisation" of Earth's oil and mineral resources, which he said is driving bloody conflicts.
"The destiny of humanity risks being tragically compromised without a change of direction in the assumption of political responsibility and without respect for institutions and international agreements," the pope said on Tuesday.
In a speech to Equatorial Guinea President Teodoro Obiang Nguema Mbasogo and other political leaders, the head of the 1.4-billion-member Church said: "God does not want this."
He added: "His holy name must not be profaned by the will to dominate, by arrogance or by discrimination. Above all, it must never be invoked to justify choices and actions of death."
Leo, visiting Equatorial Guinea on the last leg of an ambitious 10-day tour, has taken on a new forceful speaking style during his time in Africa, issuing sharp denunciations of war, inequality and global leadership.
He warned on Monday at an event in Angola that many people in the world were being "exploited by authoritarians and defrauded by the rich".
Obiang has led Equatorial Guinea since 1979 and has been widely criticised as one of the most repressive leaders in the region.
His government denies allegations of human rights abuses and corruption.
Leo's comments lamenting the use of religion to justify violence echo remarks he made in March, when he said God rejects prayers from leaders with "hands full of blood".
Leo has emerged in recent weeks as a growing critic of the war.
More than 70 per cent of Equatorial Guinea's population of 1.8 million identify as Catholic.
