Ashley has come under fierce criticism from Newcastle fans, following his failure to invest heavily in the January transfer window.
Newcastle made three signings last month, but every one of the additions was brought in on loan.
Mitrovic was temporarily sent out to Fulham, in an attempt from Benitez to make room for his new additions.
However, the Serbian forward claims that he has no hard feelings towards Newcastle, and insists he wants them to stay in the Premier League.
“For me Newcastle is such a big club and he [Benítez] knows it as well,” Mitrovic says.
“It has an amazing stadium and fans, it deserves to be in a much better position than it is now. Benítez saw the big potential of this club. I hope they stay in the Premier League, they deserve this.
“I never met Mike Ashley, he was my boss and I have to respect him. I will say Newcastle has a big history and I hope the club will be where it should be.”
Sections of Newcastle fans were frustrated when Mitrovic was loaned out to Fulham, as they feel he still has a lot to offer.
The target-man has barely been used by Benitez, but his passion for Newcastle has made him a firm fans’ favourite at St. James’ Park.
Mitrovic made his Fulham debut in their match against Nottingham Forest last weekend, which they won 2-0.