The 29-year-old scored 15 goals in 29 appearances after joining the London side on a season-long deal in August.
"We are working hard for a positive conclusion," QPR chief executive Lee Hoos told the club website.
"I wouldn't normally make any comments regarding potential transfer targets but in this instance it is important our supporters know we are keen to sign Nahki on a permanent basis."
"Our current valuations on the player are far apart and we cannot agree to a deal which will leave us in breach of FFP (Financial Fair Play regulations, which are now known as profit and sustainability rules)," Hoos added.
"We must ensure any agreement is financially viable for QPR."