Coach Arnold remains positive despite Iraq's defeat to Norway
Norway's Erling Haaland opened the scoring in the 29th minute and while Aymen Hussein momentarily equalised for Iraq, Haaland restored their lead before half-time.
Leo Ostigard added a third in the 76th minute and Hussein's late own goal rounded off the scoring.
Iraq are playing at the World Cup for the first time in 40 years and Arnold said he was heartened by their performance.
"We applied good pressure on Norway," he said. "But a few mistakes against players at this level will always punish you. So we need to take lessons from our errors."
The Australian said Norway's second goal, which came from a weak backward pass to Iraq goalkeeper Jalal Hassan, was a pivotal moment.
"It likely affected the players mentally," said Arnold. "I attempted to lift their spirits and remind them it is in the past, and we have to move on from it."
Despite the defeat, Arnold said Iraq are still firmly in the running to qualify for the knockout stage.
Norway top Group I on goal difference, with France also on three points following a 3-1 win over Senegal.
Given that the best third-placed teams also progress under the World Cup's expanded 48-team format, Arnold said there was no cause for alarm.
"We are in a group phase, there are nine points up for grabs," he said. "We have to take all the positives from today and prepare ourselves for the next game.
"There remains the chance of finishing third. Three points ought to be sufficient to progress."
Arnold also praised the efforts of Hussein, who had a season plagued by injuries.
"For him to complete 90 minutes with such energy, scoring the goal was obviously fantastic," he said.
With France next up, Arnold urged fans to continue supporting the team.
"Take pride in the players," he said. "Keep backing the lads and remain cheerful."