Griezmann scored twice as the Spanish giants overcame Marseille 3-0 in Lyon on Wednesday night.
After the final whistle Simeone, who had to watch the victory from the stands, admitted the forward could soon be on his way – but insisted his side would improve without their talisman.
'Antoine – if he stays we'll continue to grow and develop,' the Argentinian said.
'If he goes then great, he's given a lot to us over the years. Even without him we'll continue to grow.'