They were approached by a man at around 4.20am on Wednesday morning near the exit of a train station where they were waiting for a train back to their hotel in Torremolinos, police sources told local newspaper Diario Sur.
The teenage girls, who were spending a week's holiday on the Costa del Sol, told police that the man had approached them and started talking, even though they did not understand what he was saying.
They described how the man suddenly lunged at them and began touching them. The girls managed to free themselves and run away from him.
They went to the Astoria hotel from where they called local police, who mounted a search for the suspect, sending his description around local police patrols.
Local police took the girls to the train station to put them on a train back to Torremolinos when they got a call from the security team at the same train station saying they had seen the suspect.
They obtained a positive identification from the girls and arrested the man for sexual assault.