Martinez has been linked with Chelsea, Tottenham and Liverpool
Chelsea were heavily linked with Martinez in the summer, as were Tottenham. Liverpool are also reported to be interested in the 28-year-old, who has scored 34 goals in 40 games for the Portuguese side.
"The years are passing and one day I hope to make a good transfer," Martinez, who has a €40 million buy-out clause in his contract, said. "It clearly depends on Porto, a club that sells its players so well.
"Leaving or staying depends on Porto but I will only go if there is something concrete."
A move to west London is believed to be favoured by Martinez, and Chelsea manager Jose Mourinho was in Brussels on Thursday night to watch Belgium's friendly with Colombia - reportedly to run the rule over Martinez's international team-mate Radamel Falcao.
And Mourinho had the chance to watch Martinez in action when he came on as a 71st-minute substitute for Falcao.
Borussia Dortmund and Napoli have also shown interest in Martinez.