Martinez has impressed during the past two seasons at Porto and his prolific form in front of goal has prompted speculation of interest from across Europe.
Several Premier League clubs, including Arsenal and Liverpool, have been linked with the Colombia international, while Atletico Madrid are also reported to be keen after selling Diego Costa to Chelsea.
The 27-year-old, who scored twice in Colombia’s World Cup group stage win over Japan, has a further two years to run on his Porto contract and is waiting to see what unfolds.
“Right now, I don’t know what will happen,” Martinez told Colombian radio station La FM. “I have two more years on my contract with FC Porto.
“There is interest from some clubs, something that is perfectly normal when a player is performing well, but I always have to take into account the fact I am under contract and I have to respect it.
“Only time will tell what will happen.”