However, Scaloni said in January that he had a "good feeling" about Messi's possible return from his self-imposed exile, and included him along with 30 other players.
"Leo has been selected, we'll decide later if he plays one game or two," Scaloni told reporters in Buenos Aires. "I will make that decision."
Messi is Argentina's leading goal scorer with 65 goals but he is often criticised for not reproducing his club form for the national side.
He joins a squad featuring four goalkeepers, 10 home-based players but no Sergio Aguero, Gonzalo Higuain or Mauro Icardi.
West Ham United midfielder Manuel Lanzini also returns to the squad for the first time after suffering a knee injury days before the World Cup that ruled him out of action for nearly nine months.
Squad
Goalkeepers: Agustin Marchesin, Juan Musso, Esteban Andrada, Franco Armani
Defenders: German Pezzella, Gabriel Mercado, Juan Foyth, Nicolas Otamendi, Walter Kannemann, Nicolas Tagliafico, Marcos Acuna, Gonzalo Montiel, Renzo Saravia, Lisandro Martinez
Midfielders: Leandro Paredes, Guido Rodriguez, Giovani Lo Celso, Manuel Lanzini, Roberto Pereyra, Angel Di Maria, Matiaz Zaracho, Ivan Marcone, Domingo Blanco, Rodrigo De Paul
Forwards: Lionel Messi, Gonzalo Martinez, Paulo Dybala, Angel Correa, Lautaro Martinez, Dario Benedetto, Matias Suarez.
(Reporting by Andrew Downie in London and Rohith Nair in Bengaluru; Editing by Christian Radnedge)
