"I'm surprised they don't put the player's health first," national team doctor Donato Villani, who is in Europe, was quoted as saying in the sports daily Ole.
"I'm really very disappointed that the people of Bayern Munich...did not consider the consequences this decision might have," said Villani, who added a footballer with such an injury needed five to six weeks' recovery before resuming competition.
Wearing a face mask, Demichelis came on for the last eight minutes of Bayern's 2-1 home defeat by VfB Stuttgart on Saturday and is in the squad to play Manchester United in the Champions League quarter-final first-leg match on Tuesday.
Demichelis was injured when Michael Ballack hit the central defender in the cheek with his knee during Argentina's 1-0 win in Munich on March 3, but is desperate to begin playing again in order to earn a place in Diego Maradona's World Cup squad.
The 29-year-old was distraught after being dropped from the national squad just before the 2006 tournament in Germany.
Argentina begin their World Cup campaign against Nigeria in Johannesburg. They also face South Korea and Greece in Group B.
