At the race in Budapest, Sebastian Vettel finished third with Charles Leclerc in behind, but the duo were well off the pace of the front runners Lewis Hamilton and Max Verstappen, who put on a superb show before the Brit eventually claimed the flag.
Ferrari are the only one of the top teams yet to taste race victory in 2019, with Mercedes winning 10 and Red Bull winning two.
Wolff believes that could potentially change in Spa, however.
“It’s a track that probably doesn’t suit them very well,” Wolff said of the Scuderia in Hungary last weekend.
“They have a very strong engine and less drag, and that’s why we will see a very strong Ferrari in Spa and in Monza.
“I have no doubt that the conversation could be totally different than the one we’re having right now.”
Formula 1 may be in its summer break at the moment, but Wolff insists the team have been working hard to try and prepare for Belgium as they can’t take their leading position for granted.
“It’s going to be difficult for us and that’s why it’s about enjoying the moment and starting [last week] we have to sort out our problems in order to be competitive at Spa,” he added.
After the opening 12 races of the 2019 season, Mercedes lead the constructors’ championship by 150 points ahead of Ferrari.