Jelavic completed a move to Humberside after finding first-team opportunities at Everton limited this season due to the prolific form of on-loan Chelsea striker Romelu Lukaku.
But Martinez, who signed former Celtic winger Aiden McGeady from Spartak Moscow earlier in the window, insisted he will only move for a player who fits the profile of what he is looking for.
"What is important is that Aiden McGeady arriving has given us a bit more strength in the wide areas and there are many flexible players who can fill into that number nine position," Martinez told Everton's official website.
"But it would be an area that we are looking at before the window closes.
"We are looking at the options to see if there is a player with the right profile who would fit into the squad."
Jelavic moved to Everton from Rangers for a fee in the region of £5million on the last day of the January transfer window in 2012.
But the 28-year-old had become increasingly unsettled this season due to a lack of playing time amid fears his place in the Croatia squad for the 2104 World Cup was in jeopardy.
Martinez said the decision to leave Goodison Park was entirely in the hands of Jelavic once Everton had accepted a bid for his services.
"We agreed the deal (with Hull) and it was down to Nikica to make his decision," Martinez said. "I do believe when I spoke to Niki that he was clear that he wanted to join Hull.
"He felt he would get the opportunity to play the games he needs ahead of the World Cup."
Speaking after completing the move to Hull, Jelavic said: "As soon as the manager called me, I realised straight away that he was really interested in signing me and that it is a great opportunity for me to come here."