The 23 players still in Tignes, where France are on a week-long training camp, should become Domenech's official 23-man squad.
"We trust the 23 players who are here," Domenech, who has until June 1 to name his squad, said in a video posted on the French Football Federation's website.
Domenech had taken 24 players to Tignes because of a question mark over the fitness of Gallas, who has been sidelined since late March with a calf muscle injury.
The 24 became 23 after Diarra was ruled out of the June 11-July 11 finals in South Africa on Saturday because of a genetic blood disorder causing chronic fatigue.
Gallas has been training normally for the past few days.
"It's complicated to take somebody out and we've had Lassana Diarra who's had a real problem," Domenech added.
"Then we found ourselves with 23 players so we no longer needed to make a choice because that group here keep showing us that we can trust them."
France, who made an early exit from Euro 2008 and have kept frustrating their fans since, have looked surprisingly relaxed and confident since arriving at this scenic ski village.
"Those 23 players will take us all the way," said Domenech, whose team will play Costa Rica on Wednesday in Lens in the first of three warm-up games for the finals, where they will face hosts South Africa, Mexico and Uruguay in Group A.
Squad:
Goalkeepers: Hugo Lloris (Olympique Lyon), Steve Mandanda (Olympique Marseille), Cedric Carrasso (Girondins Bordeaux)
Defenders: Bacary Sagna (Arsenal), Patrice Evra (Manchester United), William Gallas (Arsenal), Eric Abidal (Barcelona), Sebastien Squillaci (Sevilla), Marc Planus (Girondins Bordeaux), Gael Clichy (Arsenal), Anthony Reveillere (Olympique Lyon)
Midfielders: Alou Diarra (Girondins Bordeaux), Jeremy Toulalan (Olympique Lyon), Florent Malouda (Chelsea), Yoann Gourcuff (Girondins Bordeaux), Abou Diaby (Arsenal)
Forwards: Thierry Henry (Barcelona), Nicolas Anelka (Chelsea), Andre-Pierre Gignac (Toulouse), Franck Ribery (Bayern Munich), Sidney Govou (Olympique Lyon), Djibril Cisse (Panathinaikos), Mathieu Valbuena (Olympique Marseille)
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