The Germany international has a contract with BVB until June 2017, but will be available for a limited fee release clause of £27.7m in the summer of 2015.
Dortmund are keen to hold on to Reus, though, and have offered the 25-year-old a payrise in an attempt to convince him to agree to remove the buyout clause from his current deal.
However, contract talks have so far been unsuccessful and the attacker's representative has refused to rule out a move elsewhere.
"Marco would make any big European team stronger," Hebel was quoted as saying by Bild.
"That's why it's completely normal that a number of these major European teams are interested in signing him.
"But his main priority for now is to get back to top fitness and return to the pitch. Everything else is not important at this stage."
Reus, who missed Germany's successful World Cup campaign due to injury, has been linked with clubs such as Bayern Munich, Barcelona, Real Madrid, Manchester United and Liverpool in the past few months.