Both were named on Tuesday in the country’s 23-man squad for the tournament along with Juventus forward Paulo Dybala, who made the cut despite scoring only five goals in 30 league appearances this season.
There was no place for Inter Milan striker Mauro Icardi, the Nerazzurri’s leading scorer this term with 11 goals.
Messi, who took a nine-month break from the national team after the World Cup before playing again in a 3-1 defeat to Venezuela in March, has scored 50 goals in all competitions this season for Barcelona heading into Saturday’s Copa del Rey final against Valencia.
The Argentina captain finished as La Liga’s top scorer with 36 goals in 34 appearances as Barca retained the Spanish crown.
Argentina director of national teams Cesar Luis Menotti said in Tuesday’s news conference that “Messi is among the greatest in the history,” while Scaloni hailed the strength of his squad.
“We believe that we have selected the best players right now for what is an important time for the national team,” Scalonisaid. “It causes me pain for those that haven’t made it but I could only select 23.
“When you have so many good players to choose from, there are always doubts. But I made my decisions on what was best for the team. We know what we want and we know what our path has to be.”