Russia and England have applied separately to stage the 2018 and/or the 2022 World Cup while Spain and Portugal and Netherlands and Belgium have made joint bids for one or both.
Australia, Japan and United States have also bid for the 2018 and/or 2022 edition and South Korea, Indonesia and Qatar have all applied to host only the 2022 version.
Blatter said he had talked over the deal proposal with Michel Platini, president of European football's governing body UEFA.
"There is a movement at the moment among the various candidates that in the end it would be a good solution ... if the candidates for 2018 would only be those from Europe," said Blatter at a news conference.
"It's not been finally decided but it's the idea, also to make the work of FIFA easier and especially that of the executive committee," he added after meeting Spanish Prime Minister Jose Luis Rodriguez Zapatero in Madrid.
"It would also possibly make the work of the different organisations applying for the World Cup easier."
World soccer's ruling body FIFA need bid documentation by the end of May and will study them in June and send out groups of specialists to visit candidate nations and assess their ability to stage the event successfully, Blatter said.
FIFA will announce which nations will host both tournaments in Zurich in December.
