The Goodison Park outfit have shipped 10 goals in three Premier League matches this season and are without a win.
Everton spent £28million to bring Romelu Lukaku to the club from Chelsea while Muhamed Besic, Samuel Eto'o, Gareth Barry and Christian Atsu have also joined.
No money was spent on defenders, though, and after Everton lost 6-3 to Chelsea last month, Martinez could have turned to the transfer window for additions.
But the Spaniard insisted it never crossed his mind and claimed he was happy with the club's defensive options.
"It was never the case that I would go into the market to add a player in that department," Martinez told Everton's official website.
"We have very good options and the players are ready to perform now.
"You look at Phil Jagielka and Sylvain Distin and the experience and know-how that they have. Then you have Antolin Alcaraz and John Stones.
"So we have four centre-halves that I couldn't be happier with.
"Now all we need to do is get them enjoying their football and getting that confidence back."
Everton's next Premier League match is at West Brom on Saturday.
