The Premier League's top two teams are reportedly keen on signing the Argentine, having both been linked with submitting offers during the ongoing transfer window.
However, agent Jose Irribaran has insisted that he has had no contact from either Manchester club.
"I think any team in the world would like to have Gaitan. However, at this moment neither side has been in contact," Irribaran told Antena 1.
"Gaitan is thinking only of Benfica and not the rumours in the papers. His objective is to play and to develop as a player.
"The footballer is happy at the club and wants to win titles in Benfica. He's content in Portugal and that is very important to how he performs on the field."
Gaitan, 23, joined Benfica in 2010 from Boca Juniors.