The Stade Louis II outfit realise both Primera Division stars are out of their reach for now and insist that they will sign only five or six players this summer
The Stade Louis II side have already secured the services of Ricardo Carvalho, Joao Moutinho and James Rodriguez in recent weeks and are expected to announce the capture of Radamel Falcao shortly.
Despite their remarkable spending, however, Dhondt has made it clear that their end-of-season spree is nearing its end.
"Messi and Cristiano Ronaldo are not very realistic options. I don't think they are for sale," he told Het Nieuwsblad.
"Monaco are a strong brand, though, just like Paris [Saint-Germain]. The [tax-free] region is a plus for us and players will take that into consideration when making a decision.
"We will not be signing an entire team as we already have a strong core. We might sign four, five, or perhaps six players, but only players we really need.
"We could use some reinforcements in defence. Don't believe everything you read in L'Equipe, though."
The Monaco director then went on to discuss his side's ambitions and made it clear that owner Dmitry Rybolovlev understands that it will take time before they can challenge for the Champions League title.
"We are full of ambition," he added. "We want to be a major player in Ligue 1 and make it into Europe right away.
"The owner realises that winning the Champions League will take time. We want to surprise the world, but we all know that this is a long-term project."