Atletico's all-time leading goalscorer, who has scored five goals in six Champions League games this season, was replaced by Angel Correa (28) in the 78th minute.
"He (Griezmann) sprained his ankle and we hope it will be just a sprained ankle," Simeone told reporters.
Atletico's injuries are piling up ahead of next week's Copa del Rey semi-final second leg against Athletic Bilbao.
Defender Jose Maria Gimenez (29) was also injured a minute after half-time on Tuesday, while midfielder Thomas Lemar (28) and winger Marcos Paulo (23) are also sidelined.
Simeone also said he was optimistic about his team's chances of advancing to the Champions League quarter-finals when they host the Serie A leaders in the second leg on March 13th.
"Going beyond the defeat, we've proven that we're able to compete. We know what we'll face," Simeone added.
"After playing against them now we know how they play. Now we hope that when the time comes we'll be in top shape and we'll compete the way this tournament demands."
Atleti face LaLiga's bottom club Almeria on Sunday - follow the game with Flashscore.
