Nigeria lost 3-2 against Portugal who showed superior technical depth.
“We are all disappointed we lost the game but we are also looking forward to our next game against Cuba on Monday,” said Ajagun.
Nigeria will next face Cuba on June 24 and Ajagun is hoping for an improved performance.
“We will improve in our next game and score the goals that will get us back in the competition,” he said.
Nigeria’s chief coach, John Obuh also spoke about 3-2 defeat in the hands of Portugal and stressed on the need for his side to be prepared to get a win against Cuba.
“It was a keenly contested game but unfortunately we lost, this was not what we had hoped for.
“We have to take the defeat in good faith so as to face the next game because we have to qualify to the next round,” he said.
Monday’s game between Nigeria and Cuba at the Kadir Has Stadium, Kayseri kicks off at 4pm.
Portugal opened a two-goal lead after Bruma and Aladje scored in the 30th and 34th minutes to give the Iberians a deserved advantage going into the break.
Nigeria reduced the tally with Ajagun hitting a brace in the 57th and 67th minutes but the Flying Eagles suffered a brief lapse in concentration, allowing Bruma to steal in and complete his brace with a smartly-taken goal 69th minute.