The pope decried "the resurgence of nationalistic tendencies at odds with the vocation of international organisations to be a setting for dialogue and encounter for all countries."
The Argentine pontiff highlighted "a certain inability of the multilateral system to offer effective solutions to a number of long unresolved situations, like certain protracted conflicts."
Today's rise to power of populist and nationalist leaders mirrors what happened between the two world wars, when the United Nations' predecessor, the League of Nations, failed in its efforts to prevent conflict, Francis said.
"The reappearance of these impulses today is progressively weakening the multilateral system, resulting in a general lack of trust, a crisis of credibility in international political life, and a gradual marginalisation of the most vulnerable members of the family of nations," he said.
"The abuse of minors is one of the vilest and most heinous crimes conceivable. Such abuse inexorably sweeps away the best of what human life holds out for innocent children, and causes irreparable and lifelong damage," he said.
Francis swore to "render justice to minors", and said a meeting of the world's bishops in February was "meant to be a further step in the Church’s efforts to shed full light on the facts and to alleviate the wounds caused by such crimes."
A litany of child sexual abuse scandals has rocked the Catholic Church, which has 1.3 billion followers around the world.
In December the pontiff had vowed the Church would never again treat abuse allegations without "seriousness and promptness", calling on abusers to hand themselves in to police.
Steady drip of scandal
The Argentine has struggled to resolve the problem as the steady drip of scandal corrodes the church's authority amid sharp divisions in Rome over how to handle the fallout, and an apparently endless stream of bad news.
In the latest case to shake the Catholic Church, the highest-profile Catholic cleric to be caught up in a paedophile scandal in France went on trial on Monday charged with failing to report a priest who abused boy scouts in the 1980s and 90s.
Cardinal Philippe Barbarin, the archbishop of Lyon, in central eastern France, is accused along with five others from his diocese of helping cover up abuse in one of the parishes in the area.
On Friday the Vatican confirmed that an Argentine bishop who has held a senior position at the Holy See since 2017, is under preliminary investigation over sex abuse claims.