Catalonia's regional police force, the Mossos d'Esquadra, cordoned off the area and sent a bomb squad to check a "suspicious" van with two people inside it that was parked near the church.
They announced the operation on Twitter and asked local residents to stay indoors but shortly after said that no explosives had been found.
"It is a false alarm. Situation has been normalised in Sagrada Familia," the regional police force said in a Twitter message. No arrests were made, they added.
Finalizadas comprobaciones en Sagrada Família. Se trata d 1 falsa alarma / It is a false alarm. Situation has normalized in Sagrada Família— Mossos (@mossos) September 12, 2017
Police had closed a nearby metro station while they inspected the van and closed several nearby streets.
Spanish media said locals and tourists were ordered away from cafe and bar terraces and told to take refuge inside premises.
The incident comes less than a month after 16 people were killed in two attacks using vehicles and knives in Barcelona and a nearby seaside resort.
The attacks were claimed by the Islamic State group.
The Sagrada Familia church, designed by Spanish architect Antoni Gaudi, attracts millions of tourists from around the world every year.