The 26-year-old forward is refusing to rule out the prospect of leaving the Portuguese giants this summer amid strong speculation linking him with a move to Napoli.
The Colombia international, 26, has been repeatedly linked with a move away from the Portuguese champions throughout the offseason, with Napoli among those said to be keen on the striker.
Porto boss Paulo Fonseca recently poured cold water on the speculation linking Martinez with a move away from Estadio Dragao, but the player himself, who has a €40 million release clause, hinted that a transfer remains a distinct possibility.
"I'm very calm about my situation here, and I will continue to do my job and respect my contract with Porto," Martinez told reporters. "I prefer not to think about the speculation. I'm fine at Porto, but I cannot rule out the possibility of leaving."
Martinez, whose contract expires in 2016, joined the Portuguese giants last summer and netted 29 times in 38 appearances in his debut season.