Hazard moved from Chelsea to Madrid last summer for a fee around €100million.
But the 29-year-old is yet to shine at the Santiago Bernabeu, after reporting for the season overweight.
Hazard has also struggled with injuries and is currently recovering from a foot problem.
So far, the Belgian has one goal and four assists in his first 13 appearances for his new club.
“If he’s not playing well, something’s going on at Madrid because he is really good,” Guardiola said on Post United.
“Not a top player, another level above. What we saw in England… he is world class. But the whole world knows that you need a period of adaptation.”