Falcao only joined Claudio Ranieri's side in May, but has been constantly linked with a move to Premier League side Chelsea.
However, Vasilyev says the 27-year-old Colombia international forward is integral to their plans of becoming a major European force.
Vasilyev said: "People believe it is suspicious to have such a great player in France. They ask 'When will he leave? In January or in June?'
"We have always stated that Falcao is essential to our project. He allows us to hire other players and build a whole team."
The vice-chairman failed to rule out the possibility of signing Manchester City's Vincent Kompany and Barcelona goalkeeper Victor Valdes.
"Vincent Kompany or (Porto defender) Eliaquim Mangala? I won't confirm we could hire them. We are also thinking about younger players," he said.
"People talk about Victor Valdes, because he will be a free agent and he is a friend of Eric Abidal. That was the link.
"Valdes is a great player, I can't say more."