Mexico are allowed only to field what is effectively an under-22 side at the Copa America because of rules imposed by CONCACAF, the federation it belongs to, which governs football in North and Central America and the Caribbean.
CONCACAF is worried that if its teams send full-strength squads to the Copa America, they will field only under-strength teams at its own regional tournament, the Gold Cup.
This year's Gold Cup was played in June, just before the Copa, and Mexico, fielding a full-strength squad, won it.
But the young Mexican squad at the Copa has struggled to hold its own against the stronger South American teams.
Mexico were beaten by Chile and Peru in their opening two matches and are the only side in the tournament without a point.
"I hope this is the last time that Mexico come to a Copa America with a squad with an age limit," Tena, who is Mexico's assistant coach but is in charge for the Copa, told a news conference in Buenos Aires ahead of his side's last Group C match against Uruguay.
"It would have been very interesting to see our full team, which had such an amazing Gold Cup, playing against teams as strong as those that are playing here."
Mexico have to beat Uruguay on Tuesday to stand a chance of squeezing into the quarter-finals of the competition.
