Lukaku's agent Christophe Henrotay has claimed that he has held talks with Spurs over a potential transfer in the summer, but Mourinho believes that it is the wrong time to discuss the Belgian's future.
The 51-year-old told reporters: "Have we had any approaches? No. I don't think that it's the time to speak about it.
"He's a Chelsea player, but at the same time, he's an Everton player until the end of the season. We want to respect that. Everton are a good club for a loan. Our player is there and our player is playing."
Lukaku has scored 13 times in 26 appearances during his time with the Toffees.