The mural appeared Thursday, 13 days before the two leaders are scheduled to meet at the Vatican.
According to Reuters, the mural was painted on paper and then fixed on a wall near the Vatican.
The piece of work shows Francis with a bright yellow halo and wearing a crucifix around his neck. It also shows Trump with a gold watch and a gun in a holster. The mural shows the pair embracing each other and engaging in a mouth-to-mouth kiss.
The caption on the sash of the pope's cassock reads "The Good Forgives the Evil." It is signed "TVBoy," who is believed to be an Italian street artist.
An American tourist said: "It is very provocative but not too shocking for someone coming from America."
Reuters said murals depicting the pope are usually taken down by a group of Rome sanitation workers called "The Decorum Squad".
The group have removed a mural depicting the pope as Superman and another one of him as a graffiti artist.
