He will also miss the first match of the play-offs, should Millwall, who sit in sixth spot in the Championship table, maintain their place in the top six.
The loss to their London rivals was the first time Millwall have tasted defeat since Cahill made an emotional return to the club where he started his career in January.
Millwall's great form has seen Cahill not start a game for Neil Harris' side and the 38-year-old has played just 65 minutes of football in the 14 matches he has been involved in since leaving A-League side Melbourne City.
Bert van Marwijk's Socceroos squad will assemble in Turkey for a four-week, pre-World Cup training camp, on May 19.
The Dutchman will name an extended squad which has to be reduced to 23 by June 4, with Australia kicking off their campaign against France on June 16 in Kazan.
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Despite being the Socceroos' record goalscorer, Cahill is far from certain of a place in van Marwijk's squad and played for just 27 minutes in the two recent friendlies against Norway and Colombia.
Should Millwall miss the play-offs, Cahill will get just one opportunity to stake a claim for a place in the squad in a friendly against the Czech Republic in Vienna on June 1.
A second match against Hungary will be played in Budapest on June 9.
