Griezmann made a deadline day loan move to the Spanish capital from Barcelona, where he endured an underwhelming two-year stint.
The 30-year-old France international is yet to score in four appearances for Atletico Madrid so far and was taken off after 66 minutes against Getafe in La Liga on Tuesday.
Atletico Madrid were trailing 1-0 when Griezmann was taken off but rallied to claim a 2-1 win at the end of proceedings thanks to Luis Suarez’s brace.
Simeone has acknowledged that this Atletico side is different to the one Griezmann left two years ago and will take time for him to adapt.
"It is normal. He was very enthusiastic to return," Simeone told reporters after the game.
"He is in the process of adapting to this Atletico, which is not the same as the one he left but I have no doubts that it will be what we expect. We are fortunate to have him.
"Atletico generated other things last season… now we understand that with the players we have these systems can also enter.
"The team has more associative play. We are on a path for everyone to adapt, not only Griezmann, but also Rodrigo [De Paul]. Today he did very well. He came on to give us more stability."
Griezmann scored 133 goals in 257 appearances in his first spell at Atletico Madrid, winning the Europa League, Spanish Super Cup and UEFA Super Cup.
