The 3-2 defeat at Newcastle on Sunday was their third straight league loss and fifth in seven games, leaving them 12th in the table and just five points above the relegation zone.
“We can’t feel sorry for ourselves – we need to make sure that we get better in what we do,” said Martinez. “(For Newcastle’s second and third goal) we gave the ball away when we should have been a bit more cute, showing a bit more maturity.
“I know we have got young players in the squad, but it’s an opportunity to learn from those moments. We can’t just keep giving cheap goals away in that respect because it becomes a harder game.”
Arouna Kone, whose time at Goodison since joining in 2013 has been blighted by a long-term knee injury, scored his first goal for the club at St James’ Park on his first Premier League start.
“You can see what he brings – he’s a completely different striker to the others we have at the club,” added Martinez.
“He holds the ball up, he gives you a real platform, his intensity in the box to get on the end of crosses is very, very good and to get a goal so early coming back after a long absence is very pleasing.
“It’s a reward that he deserves. It’s just a shame that he couldn’t celebrate a good victory with it.”