Fifa president Gianni Infantino said last year the expansion from 32 teams could be brought forward from 2026 to the 2022 tournament in Qatar.
The change would have required Qatar to share hosting duties with other countries in the region.
World football’s governing body said after a “thorough and comprehensive consultation process” the change “could not be made now”.
Infantino has been a strong advocate of the expansion and said the World Cup has to be “more inclusive”.
Fifa also said it explored the possibility of Qatar hosting a 48-team tournament on its own but has decided not to pursue those plans as there was not enough time “for a detailed assessment of the potential logistical impact”.
In November, Uefa president Aleksander Ceferin said adding 16 teams to Qatar 2022 could create “many problems” and described the idea as “quite unrealistic”.
The expansion in 2026 will see an initial stage of 16 groups of three teams precede a knockout stage for the remaining 32.
The 2026 World cup will be co-hosted by USA,Cannada and Mexico.