Eriksson has included four naturalised players for next week's friendly international against his native Sweden -- Argentine-born Matias Vuoso and Lucas Ayala, and Brazilian-born Leandro Augusto and Antonio Naelson.
"I think that if they have quality and a Mexican passport, they have to be in the Mexican national team," the former England coach told reporters on Wednesday.
"Nobody told me this was prohibited.
"It's a little bit difficult for me to understand all this. If I don't select Vuoso or Naelson, they criticise me; if I pick Lucas Ayala, they criticise me, it doesn't seem fair.
"Of course, there's talent in Mexico," he added.
"The players who are here now are for me the best 23 we have at this moment. There are no favourites, nor do I pick my friends."
The Swede has also been under fire over his team's poor recent performances and results.
Mexico sneaked into the last round of the CONCACAF World Cup qualifying tournament on goal difference from Jamaica and behind Honduras, losing away games to both sides in the process.
They kick off the final round, a six-team mini-league, with a tough tie away to arch-rivals United States on February 11.
The Mexican championship pays the highest wages in Latin America and has long attracted players from around the region.
Many settle and raise families in the country and obtain Mexican nationality.
Eriksson's predecessors, Ricardo La Volpe and Hugo Sanchez, also regularly included naturalised players in their squads but it remains a thorny issue.
