The Portuguese outfit boast a number of players on their books who are said to be attracting interest from afar.
The likes of Diego Capel, Rui Patricio and William Carvalho have all been heavily linked with clubs in England - including Liverpool, Manchester United and Chelsea.
Sporting are, however, prepared to block any bids during the winter window in an effort to keep their table-topping squad intact.
De Carvalho told A Bola: "The club has decided that there will be no sales in January.
"The club is leading the division for the first time in nine years and we are determined to fight for the title.
"Only if a ridiculous offer is put in for a player will it be studied."
Sporting also have no plans to recruit in the New Year, with coach Leonardo Jardim happy to work with those already at his disposal.
De Carvalho added: "There will not be any entry of players. We have a group that are true men and true warriors and who are honouring the shirt.
"There is a great deal of confidence in Leonardo Jardim and his technical team and the trust they have in every player in the squad.
"We have a clearly defined project and are extremely pleased with these players."