The campaign ended with defeat in the Europa League final to Sevilla.
But Lukaku posted to social media yesterday: "First of all I want to say thank you for all what you guys have done for my family and myself. This year as a team we grown a lot together and it's an honour to represent a club that I loved since I've been a kid.
"Yes what happened in the final p***ed me off but I will fight back. I never had s*** the easy way in life as many of you know and this experience will make me stronger.
"One thing is for sure Inter is not dead and this experience will make us better as a team! There's unity and we're heading the right direction.
"To the fans I want to say thank you for being so supportive every game home or away, I love you guys. I appreciate the messages I've got.
"We will be back sempre forza Inter."