A witness, named Claudia, told CN5 the tourists "let him die".
"He was young and came to the shore," Claudia told the Spanish-language broadcaster, according to National Geographic.
"They could have returned him to the water - in fact, he was breathing. But everyone started taking photos and touching him. They said he was already dead."
This is the second time in a year a dolphin has died after being hassled by selfie-seeking tourists in Argentina.
In February last year, tourists at the beach resort of Santa Teresita were accused of killing an endangered La Plata dolphin after they paraded it along the beach for selfies, causing the young animal to overheat and die. Its tiny body was then left discarded on the sand.
The shocking incident prompted the Argentinian Wildlife Foundation to issue a public reminder about the vulnerable La Plata dolphins, which are only found off the coasts of Argentina, Uruguay and Brazil. Only 30,000 of the species are left in the world.
Its conservation is of particular concern because they tend to swim close to the shoreline, where they often become tangled in fishing equipment.
The species of the dolphin that died during Sunday's incident in San Bernardo is not known.
