Blind is entering the final year of his contract at Old Trafford and had been linked with a return to Ajax, the club he left to join United in 2014.
Ten Hag has now revealed that the club are "doing everything" to sign the 28-year-old, but hinted that a deal may not be straightforward.
"[He is] a player with a lot of experience, in the Premier League and in the Dutch national team," Ten Hag is quoted as saying by Sky Sports News.
"He is a stable personality. Just like the arrival of Dusan Tadic, this also counts as a considerable effort of the club. We are doing everything, but it also depends on other parties.
"He can handle both positions well, both as a central defender and as a controlling midfielder."
Blind made just seven Premier League appearances for United last season.