The Slovenia international has impressed at the heart of Roger Schmidt's side this season after moving from Borussia Dortmund in August last year.
Kampl's performances have caught the eye of Liga leaders Atletico, but Voller is adamant that Leverkusen will adopt the same stance with all of their star players.
"What applies to Chicharito [Javier Hernandez] and Christoph Kramer is the same for Kampl. We're not going to let anyone go," he told Bild.
"It's definitely not an issue. Kevin is delighted with us and we are happy with him. We need the player."
Kampl's agent Michael Ruhnau confirmed Atletico's interest, but says club sporting director Andrea Berta has been informed that the 25-year-old does not want to leave.
"I have referred Atletico directly to Rudi Voller and told Mr Berta that Kevin is 1,000 per cent happy to be with Leverkusen," he said to Bild.