The Franco-Dutch group warned of doubts over fuel prices, some bloated routes and uncertainty over the economic and politics.
The carrier enjoyed lower fuel prices but said this was likely to be offset over the rest of the year by pressure on revenue and by the negative impact of currency swings.
Air France-KLM reported a net loss of 155 million euros (USD 178 million) in the three-month period, which was overshadowed by a deadly attack on Brussels airport. The loss compared to a loss of 559 million euros in the same period a year earlier.
"The global context in 2016 remains highly uncertain regarding fuel prices, the continuation of the overcapacity situation on several markets and the geopolitical and economic context in which we operate," Air France-KLM said in a statement.
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"As a consequence, the group expects the forecasted savings on the fuel bill to be significantly offset in the coming quarters by unit revenue pressure and negative currency impacts."
The airline said it was sticking to its forecasts for this year, including cutting unit costs by around 1.0 per cent and a cutting its net debt -- now standing at 4.16 billion euros -- significantly.
Two suicide bombers struck Brussels airport on March 22, while a third attacker blew himself up on a metro train. The twin attacks, which killed 31 people, came barely four months after the November 13 attacks in central Paris that killed 130 people.
Air France-KLM finance director Pierre-Francois Riolacci said traffic to Paris had been affected due to "terrorist events" especially for the Japanese market.