Team Melli dropped one place to 37th after suffering a 2-1 defeat to Turkey in May and Australia moved up four spots to 36th following a 4-0 win over Czech Republic.
South Korea moved up four spots to No. 57 and Japan moved down one spot to 61st.
Carlos Queiroz’s men will open its World Cup campaign against Morocco on June 15.
Elsewhere, the top seven spots have remained the same with Germany staying at the summit ahead of Brazil and Belgium.
The next edition of the FIFA world rankings will be announced on July 19.