Francis is known as a lifelong football fan and card-carrying member of Argentine club San Lorenzo, but Karcher said he did not even tune in to see the nail-biting final in Brazil, which Germany won 1-0 in extra time.
"The pope was updated on the World Cup but said he wasn't going to watch it as a matter of neutrality," Karcher, one of Francis's closest associates, told Argentine broadcaster Radio del Plata.
Karcher, who is also Argentine, worked with the pope -- then named Jorge Bergoglio -- when he was archbishop of Buenos Aires.
The pope stuck to the neutrality principal ahead of the match, limiting himself to a comment about the importance of intercultural exchange on Twitter.
"World Cups bring about the encounter of people from different nationalities and religions. May sport always promote a culture of togetherness," he wrote on his @pontifex account.