The Ivory Coast international was not on board Roma's flight to the US on Monday, with Rudi Garcia's side due to face Liverpool in Boston on Thursday.
Following that, last season's Serie A runners-up will contest the International Champions Cup, havoing been drawn in Group A against Manchester United, Real Madrid and Inter.
While the 27-year-old remains in his homeland, he stated he would soon join up with his team-mates.
"Unfortunelty [sic], i can't be with the rest of the team because, i need to sort out some personal issues here in Ivory Coast," he stated via his Facebook account.
"The team management game [sic] me his full support, i should be able join my teammate soon. Thank you for understanding."
The former Arsenal man scored 12 goals in all competitions during his debut season for the club last term.