Academy manager Alan Dickens has been filling the role since Alex King left Franklin's Gardens in October.
Dickens helped the club reach their first Premiership final in 2013 before King came in that summer.
But Saints are currently ninth in the Premiership and Hewitt said: "We are unaccustomed to the situation in which we currently find ourselves."
In a message to supporters on the club website, he continued: "We remain committed to wanting to have the best possible squad and to give the coaching and backroom staff the means to provide the players with the wherewithal to bring wins to Northampton.
"A lot of work is going on behind the scenes to secure international-calibre players to bolster the squad for next season, and we are also seeking a new attack/skills coach to start as soon as their availability allows."
Having won only four of their 10 Premiership games this season, Northampton are also bottom of their Champions Cup group.
"There have been many comments on social media and online forums which accuse the club's management of being 'out of touch'," said Hewitt.
"As someone who has been a part of the Saints for the best part of 30 years I can, hand on heart, say that I can appreciate and understand the frustrations that everyone has at the present time.
"All of the staff at Franklin's Gardens have a passion to see the club succeed, whether because they were supporters long before they became members of staff, or because they have the innate desire for success that is an essential part of being a professional sportsperson or coach.
He added: "We know that there is a lot of discontent among many supporters; if there is one positive we can take it is that we all share the same passion in wanting Northampton Saints to be a successful club."
Northampton chairman Tony Hewitt says he hopes to appoint a new attack coach as soon as possible.