Atletico, who will finish fourth in the standings behind Real, runners-up Barcelona and surprise package Girona, secured their place in the Champions League, although the coach believes they could have done better.
"We have the responsibility to get into the Champions League every year. You can be left out, but you can also be champion, yet with Real Madrid, who are the best team in the world and will continue to be because they have rejuvenated the squad, it is not easy," Simeone told a press conference on Thursday.
"We have to keep working at 120% because 100% is not enough and 80% is even less to be able to get closer to them, keeping in mind that those below us are also improving."
The coach said the team lacked the right response when it mattered most, such as when they were knocked out of the Champions League after a 5-4 aggregate defeat by German side Borussia Dortmund in the quarter-finals.
"We were close to the Copa del Rey final and were expecting to reach the semi-finals of the Champions League. We created the illusion of being in a possible final and we weren't able to do it, so now we have to think about what comes next to improve things," the Argentine said.
Simeone added that while there have been shortcomings this season, he remains excited about the future and reflected on his long 12-year tenure at the club, having amassed 402 victories in 680 matches in charge.
"I have had players who have allowed me to compete as we have done since I arrived, and a coaching staff where everyone who has walked this path has given the maximum and the illusion that there is always room for improvement and growth," he said.