Ryanair profits fell by 21% to €78 million in the three months to June 30.
Average fares fell 4% due to the timing of Easter and the impact of French air traffic control strikes in June.
Revenue per passenger rose by 1% due to strong ancillary growth as traffic grew by 3% to 23.2 over the same period last year.
Unit costs rose 4% mainly due to a 6% increase in fuel costs.
However, the budget carrier said its guidance of full year profits of between €570 million to €600 million remains unchanged.
Chief executive Michael O’Leary said: “As previously guided, higher fuel costs and the timing of Easter led to Q1 profits falling €21 million to €78 million.
“Ancillary revenues grew by 25% to €357 million (27% of total revenues) driven by the successful development of reserved seating, priority boarding, and higher admincredit card fees.”
Looking forward, he said: “We expect Q2 yields to rise despite last year’s challenging (post-Olympic) comparables, although yields on close-in summer bookings have been slightly weaker in recent weeks due, we believe, to the heatwave in northern Europe.
“As ever, our outlook remains cautious for the full year as market conditions are tough with recession, austerity, high fuel costs, and excessive government taxes (most recently in Belgium) impacting air travel demand and yields.
“While we expect full year traffic to grow 3% to 81.5 million, we still have no visibility over next winter’s yields, and on the basis that the recent yield weakness in close-in summer bookings does not continue, we see no reason to change our full year profit after tax guidance.”
Shareholders recently approved an order for 175 Boeing 737-800s for delivery over a five years from September 2014.
This has allowed the carrier to raise its growth targets by 38% to 110 million passengers by 2019 with a fleet of 410 aircraft.