Viral images show the Pope warning the driver to stop the vehicle when the girl, in a white shirt and pink trousers, runs through barricades to approach him.
A guard lifts the girl up so that the pope can bless her, videos & # 39; s. Another girl follows her afterwards.
A photo of the moment shows the first girl in tears like Francis, smiling, touching her head.
"She was courageous," the Pope later told reporters. "I said:" No, let her come! "" That girl has a future ", jokingly adding:" I dare to say, "poor man! & # 39;"
"I liked that", he added during a press conference aboard the papal plane on his return flight to Rome. "That requires courage."
The Pope has not given any details about the contents of her letter.
Francis became the first pope to celebrate Mass on the Arabian peninsula. In his sermon the pope praised congregations as "a choir consisting of a large number of nations, languages and rites."
Nationals of the UAE are predominantly Muslim, but about 90% of the population consists of expats, including about 1.2 million Christians.