Speaking at the port of Arguineguín on Gran Canaria on Thursday, the head of about 1.4 billion Catholics worldwide said human dignity demanded it.
"It is not enough to manage arrivals, distribute statistics, reinforce borders or lament deaths after they have occurred," he said in an official English translation of his address.
The Canary Islands have for many years been a hotspot for migration from Africa across the Atlantic to Europe.
The phenomenon particularly shaped the islands between 2020 and 2024.
Although the number of migrants arriving by boat fell sharply last year, almost 50,000 people arrived irregularly on the Canary Islands within a single year at the height of the crisis in 2024.
The port of Arguineguín on Gran Canaria, also known as the "Port of Shame," became a symbol of the humanitarian emergency.
In August 2020, almost 3000 people were at times stranded there in precarious conditions, even though the area was designed for about 500 people.
They slept in the open air, and sanitary conditions were appalling.
At that port in the south of Gran Canaria, just half an hour's drive from the holiday resort of Maspalomas, Leo met recently arrived migrants as well as representatives of the Church and humanitarian organisations who care for them and support their integration into Spanish society.
Leo also described the refugee crisis as a test of conscience above all for Europe, which cannot proclaim human dignity while allowing itself to grow accustomed to "the Mediterranean and the Atlantic becoming unmarked graves".
He called on the international community to share responsibility on the issue.
Leo said he hoped the voices of migrants would reach those with authority in this matter, including civil authorities, parliaments, governments and international organisations.
Every boat that arrives, Leo said, brings not only migrants but also a central question for all: "What kind of world have we built, if so many brothers and sisters must risk death to seek life?"