The stopper has been in fine form again this season leading to rumours of a switch to United, as well as former club Real Madrid and Barcelona.
Casilla has been on United’s radar for the past two seasons to add competition to David De Gea’s position.
David Moyes has missed out on numerous targets since he took over at Old Trafford and it could be Deja vu for the United boss if Casilla signs a new deal with Espanol which is set to be done before the summer.
“I am not concerned about the rumours regarding my future,” Casilla said.
“I am pleased to hear my name mentioned in the press alongside Barcelona, Real Madrid and big English clubs, but my intention is to remain at Espanyol.
“I am in negotiations with the club over a new deal and I hope to reach an agreement soon.
“I don’t believe that the club are planning to sell me if they want to renew my contract that would be a lack of respect.
“I don’t have a set date for the signing of the documents, that is a matter for my agent, but I am calm.”