The 28-year-old left-back was the subject of two failed bids by former manager David Moyes during the summer transfer window, and it was rumoured that a new deal would be on the table should he remain at Goodison Park.
However, Martinez suggested that the those on the "outside" are trying to test the water for a potential bid by speculating about the England international, who has just over 18 months left to run on his current agreement.
"There's no train of thought on that at the moment," the Spanish coach told reporters. "All that matters is that Leighton is enjoying his football. That's the only thing I'm focusing on.
"I think all his performance stats have improved from last season. That, for me, is very important - someone of his age and maturity is starting to enjoy his football in a great manner.
"That's what matters to me. Everything else is just a case of trying to find an issue from the outside and see what we will comment on."
Baines has scored two goals for the Toffees this season, with both being second-half free kicks in a 3-2 win over West Ham United in September.