The Morocco international appeared to be on his way to the Eredivisie champions, but has made it clear they will have to improve their contract offer
The Eredivisie champions have already agreed terms with the Frisians over a transfer fee, but the Morocco international is not impressed with Ajax's contract offer, and has threatened to pull the plug on his proposed move if they do not match his demands.
"There is no doubt that Ajax are a great club. I do want to make a step forward, though, financially," Assaidi stated to Eredivisie Live.
"Let's cut to the chase, I want to earn a good salary. I know that Ajax have a new policy, but I will stay at Heerenveen unless they offer me a good salary.
"I still hope to reach an agreement with Ajax, though."
The 23-year-old winger previously turned down the chance to join Galatasaray, while also ruling out a move to the Russian league.
Assaidi's contract with Heerenveen runs until the summer of 2013.