Tottenham boss Mauricio Pochettino admits they struggle to compete at the top level of the transfer market.
Spurs have shown an interest in Ross Barkley and Malcom this month.
But Barkley has joined Chelsea from Everton and Bordeaux attacker Malcom is edging closer to an Arsenal switch.
"It's difficult to keep secrets," he said. "Sometimes the media knows before me the player who we are going to sign.
"That makes our job difficult. How do you keep it secret? Impossible.
"Maybe someone near the player is going to talk. Maybe you make an offer and it's used to talk with another club. It is frustrating. We can't stop it."