"Danny presented us with personal reasons that prevent him from being at the preparation camp and we accepted them," the Portuguese federation said in a statement.
Danny, who was on the scoresheet for Zenit St. Petersburg in last week's 3-1 Champions League win against Porto, has been regularly called-up to the national side since Paulo Bento took over last year.
Portugal, level with Denmark and Norway at the top of Group H, will play Iceland at home on Friday and then travel to Denmark four days later in their last two Euro 2012 qualifiers.
Goalkeepers: Eduardo (Benfica), Beto (Cluj), Rui Patricio (Sporting).
Bruno Alves (Zenit St. Petersburg), Joao Pereira (Sporting), Eliseu (Malaga), Rolando (Porto), Silvio (Atletico Madrid), Ricardo Costa (Valencia), Sereno (Cologne).
Carlos Martins (Granada), Joao Moutinho (Porto), Miguel Veloso (Genoa), Paulo Machado (Toulouse), Raul Meireles (Chelsea), Ruben Micael (Real Zaragoza), Ruben Amorim (Benfica).
Cristiano Ronaldo (Real Madrid), Silvestre Varela (Porto), Helder Postiga (Real Zaragoza), Nani (Manchester United), Ricardo Quaresma (Besiktas), Nuno Gomes (Braga).