Atletico, days after eliminating Bayern Munich to reach the Champions League final, lost 2-1 on Sunday at Levante where they have not won since 2007.
That left the Rojiblancos three points adrift of league leaders Barcelona with one game remaining and unable to overtake them because Barca have a better head-to-head record should both teams finish level on points.
"There is no type of excuse regarding our previous game," Simeone told the club's website.
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"We are finishing what has been a fantastic and enormous campaign. We were one game away from competing with Barcelona and Real Madrid," he added.
"Other years we were further away and this year we came closer. This is what makes me happy."
Atletico won La Liga in 2014-15 but lost in that year's Champions League final to Real Madrid - their opponents again on May 28 in Milan in this season's title showdown.
They have never won Europe's elite club competition but have twice finished runners-up.
"Of course, we lacked something," Simeone said of his team's overall performance in the league.
"I've told my players that I'm proud of them and that they have had a great season up to now. Now is the time to recover our strength to end the campaign in the best possible way."
Simeone, who had to watch the game at Levante from the stands because of a touchline ban, will attempt to steer the Rojiblancos to a runners-up finish in La Liga.
Atletico end their domestic campaign on Saturday at home to Celta Vigo.
(Editing by Ed Osmond)
