Romelu Lukaku's return to parent club Chelsea has left a significant void in Martinez's team as he prepares for a second season in charge at Goodison Park.
Lukaku scored 15 goals in 31 Premier League appearances for Everton last term - a haul that helped inspire the club to a fifth-place finish in the English top flight.
Martinez is eager to be reunited with Lukaku - apparently deemed surplus to Jose Mourinho's requirements at Stamford Bridge - on a permanent basis, and speculation has mounted in recent days that an agreement is in place for the Belgian to return to Merseyside.
Former Wigan Athletic manager Martinez has poured cold water on such reports, though, insisting Everton have not struck a deal with Chelsea.
However, the Spaniard made it clear that bringing in a goalscorer during this close-season remains top of his wish-list.
"There have been a lot of reports, some even saying I've told people it [a deal for Lukaku] is done, but the situation is very clear," Martinez told Everton's official website.
"We need a number nine going into the start of the season and we will make sure we sign one.
"Rom created incredible memories we'll never forget and enjoyed his time at Everton - but that doesn't mean anything between now and the end of the window.
"Everything is in the air and you can imagine there are options on the table. We will carry on working hard to assemble the strongest squad possible."
Martinez also offered an update on Muhamed Besic's protracted transfer from Ferencvaros, saying the Bosnia-Herzegovina international "already feels part of the squad" after he joined up with Everton on their pre-season tour in Asia.
"We hope things will be wrapped up for Besic soon," he added.
"There are certain details that need to be solved and once that's all done, we'll be okay.
"He trained on Saturday and that was a real positive."
