Both of Croatia's goals came from corner kicks, and Rohr has insisted that Nigeria's problems stemmed from set pieces rather than their tactical approach, which has been heavily criticised following the match.
"I think the organisation was okay. We didn't concede from normal play, we conceded from set-pieces," Rohr told reporters. "Our system was okay. We cannot play with three when there is only one centre-forward, so we played with four because Croatia had three strikers.
"What we were missing was to be more professional on set-pieces. Each game is different, we will see for the next game. We know we can play with three centre-backs but today (Saturday) was not that day."
Next up for Nigeria is a clash with Iceland on June 22, before finishing their group campaign against Argentina on June 26.