Rondon, 26, has come under the spotlight thanks to some impressive showings in Portuguese Primeira Liga and is now widely tipped to leave Os Alvinegros for greener pastures.
A Bola understands that clubs from England and Ukraine are keeping close tabs on the Venezuelan, who has now confirmed he is aware of foreign interest.
“There are many clubs interested, but my heart and soul are at Nacional, for the time being, and I only think about contributing to the team’s cause,” the forward was quoted as saying in A Bola.
Mario Rondon has a contract until June 2015 at Nacional, but it is believed the club chiefs are prepared to sell him if the price is right.
The Venezuela international has spent his entire professional career in Portugal, representing Pontassolense, Pacos Ferreira, Beira Mar and Nacional.
After scoring 10 league goals last season, Rondon has failed to find his goalscoring boots this term, having netted just once in 14 league appearances.