Herrera - who was named the Red Devils' player of the year last season - started an online war by posting a video of him playing beach football and trying out his goalkeeping skills.
Herrera's current contract expires next summer but the Spaniard is expected to sign a bumper new deal over the next fortnight.
Another United transfer narrative, surrounding the talks to acquire Real Madrid striker Alvaro Morata, has been discussed at length the past couple days.More news: Miranda Kerr Unveils Her Dior Wedding Dress for Vogue
"Too bad he is not with us but I wish him well".
"I reached the point of seeing Morata as a teammate, he was very close [to joining United]", he said.
Speaking in the mixed zone after United began their preseason tour of the United States with Saturday's 5-2 victory over LA Galaxy, Herrera said the speculation over De Gea's future was getting repetitive.
The Spaniard told Spanish radio station Cadena Cope: "I think De Gea is going to stay". We do not determine what the price is of a player of Real Madrid, Real Madrid do that.