Johnson, 23, is out of contract in the summer and was placed on the transfer list at Elland Road last month after refusing to accept a new offer.
When asked about Johnson, who insists he still wants to stay at Leeds, Martinez said: "There are going to be a lot of names thrown at us and a lot of speculation.
"I think we will speak about the window when it arrives but at the moment it is too early."
Source: PA