The Eastern Europeans ended their campaign with a 3-1 win over Iran on Wednesday following earlier defeats to eventual Group F winners Argentina and Nigeria.
"This was my last game at the World Cup," Susic told Brazilian newspaper Lancenet.
"Unfortunately there will not be another one. Sometimes it is a nice feeling to be free of obligations.
"I can decide my own fate and this is my answer."
He added: "I feel sorry for those we have disappointed.
"We should have done better by the quality of our players but now is the time for this team to look forward to Euro 2016 qualifiers.
"We lacked experience and cool heads at crucial moments in the opening two games but I cannot complain about effort. That's just football."