The defender's comments came after Wednesday's 3-1 defeat to Real Betis in Dublin, with Arsenal closing in on a £75m deal for Newcastle United captain Guimaraes this week and continuing to be linked with Real Madrid's Vinicius Junior, whose contract runs out next summer.
Guimaraes is waiting for permission to leave Newcastle's training base in La Manga to finalise the formalities of his move to north London, while any deal for Vinicius looks a tougher proposition given Madrid's determination to keep hold of him.
Asked whether Arsenal needed players of that calibre, Calafiori first turned to a member of the club's media team to check whether the Guimaraes deal had been made official before answering.
"We are on that level now. We are on top. We want to win the league again, we want to be even better than last season if we can. We need these kind of players I think," he said.
On Guimaraes specifically, he was more guarded: "It's not official, so I cannot speak about it."
Arsenal's pursuit of Vinicius has continued despite Real Madrid's efforts to tie him down to a new contract, with the Brazilian's existing deal at the Bernabéu expiring at the end of next season and negotiations between the two parties still unresolved.
Guimaraes, meanwhile, is set to become Mikel Arteta's latest signing of the summer following the arrivals of Kepa Arrizabalaga and Illan Meslier, strengthening a midfield already touted as one of the best in the division heading into Arsenal's title defence.
Calafiori himself has started the pre-season as one of Arteta's first-choice defenders, having established himself as a regular in the side that won last season's Premier League title, and his comments reflect a squad well aware that standing still is rarely enough to retain a crown in English football's most competitive division.