The three-time African champions dropped to the bottom of Group D log after suffering a loss in their World Cup opener to Zlatko Dalic’s men on Saturday.
The Super Eagles were punished from two corner kick situations in each half of the encounter - the first led to Oghenkaro Etebo's own goal with Luka Modric dispatching from the spot to double the Croats' lead.
After taking responsibility for his side’s errors in defending set-pieces, Rohr is confident of his team’s qualification from the group if they get the maximum points against Iceland.
"We are disappointed. We recognise that Croatia had the better team tonight and my young players made mistakes, again on the corners,” Rohr said after the game.
“The first goal was a corner, the second goal a penalty from a corner. There were also many fouls in the other box, they could have also given a penalty for us. Now we have to win against Iceland. If we win the next game, all is possible for qualification."
The German tacitician was unimpressed with his side’s attacking threats after managing nine shots during the encounter without finding the back of the net.
But he reserved praise for Arsenal star Alex Iwobi and Leicester City's Ahmed Musa with the latter having 'a good chance of starting' in their next fixture.
"Of course you are not satisfied when you don't score. We were satisfied with the organisation of the team defensively, but we did not have many chances to score," he added.
“Iwobi did good initially and then Musa came on and showed his speed. He has a good chance of starting the next game, we'll see."
On whether the massive support received by the Croats present at the Kaliningrad Stadium had a negative impact on his team, Rohr insists it was rather the gulf in quality between both sides.
"It was a match like in Croatia. What I like is the quality of our supports coming from so far away. It's not the number of supporters that is important, it's the quality of them.
“It was like if we played in Croatia, in Zagreb or somewhere, but it was not the reason we lost the game, it was because of mistakes. The players thanked our fans, we keep smiling and we will try to be better in the next game.”
Nigeria will be hoping to revive their qualification to the second round when they take on Iceland in their next group game at the Volgograd Arena on Friday.