The city’s new major, Ada Colau, is pursuing her goal of limiting the number of visitors and curbing any expansion of unlicensed accommodation for tourists.
Barcelona is the most popular tourist destination in Spain, with 27 million visiting last year. Tourist numbers for the first half of this year have already broken records.
Colau already has placed a moratorium on issuing licences for new hotels and hostels.
Now she has asked rental websites, such as Booking.com and Airbnb, to disclose information on owners who let their property on these websites. She is threatening to fine any if they advertise properties which are not on the Catalan tourism register.
"Everybody must comply with the same game rules," Colau said, adding that websites must not be a means “to thwart the regulations and to shelter illegal tourist apartments”.
She has the support of many local people who have complained about having to contend with noisy tourists and about being priced out of the property market due to the increase in holiday lets.
Airbnb has said it would be preferable if authorities worked with them to clarify regulations. Instead the announcement “causes further confusion for people who share their homes,” a spokesperson said.
It encouraged Barcelona to introduce “smart policies to support local residents” rather than “acting against them”.
“They should follow the example of cities like London, Paris and Amsterdam, who have introduced clear, modern rules for home sharing,” it said.
Earlier this week, Airbnb said it will begin to automatically collect the tourism taxes from guests in Paris and send them directly to the authorities on behalf of the owners.
Previously, the onus was on the host to collect the tax and then pay it.