Ashton is out of contract at the end of the season and has been linked with a move to Premiership champions Saracens.
Ashton, currently serving a four-week ban for pulling the hair of Leicester wing Alesana Tuilagi, has scored 90 tries for Saints since switching codes from Wigan Warriors in 2007, as well as racking up 15 tries in his 18 Test appearances.
Northampton are keen to hold on to the three-quarter but Mallinder told BBC Look East: "There's not an offer on the table, because his agent doesn't want to talk to us.
"We've not had discussions and I think his mind is elsewhere. If he wanted to stay, we'd talk to him.
"If any player wants to go, for whatever reason, whether that's moving to London, or a massive financial offer, we're not going to stand in their way.
"We'll shake their hand and we'll get players who want to play for Northampton."
Northampton chairman Leon Barwell has previously stated that the club will not break the bank in order to keep hold of Ashton.
But there was also positive news for Saints after Ashton's Northampton and England team-mate Dylan Hartley penned a new deal that will keep him at Franklin's Gardens until at least 2015.
Hooker Hartley has made 144 appearances since joining from Worcester in 2005, scoring 15 tries, and the increasing maturity he has shown since being made captain in 2009 has helped make him an England regular.
Hartley has guided the club to consecutive Premiership semi-final appearances, as well as last season's Heineken Cup final.
He said: "I've got a lot of ambition for myself and for the team and want to keep cracking on and I know that I need to keep improving as a player as we've got several good hookers at the club who all want to be playing first-team rugby and are knocking on the door.
"The Heineken Cup run last year is an obvious highlight of my time here so far, and Division One was good fun, too.
"But my whole time here has been a great experience and a learning curve. I've grown up here and it's a home away from home."
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