Simeone spoke positivelu of his side's attitude in Saturday afternoon's fixture, however the result fell significantly short of expectations, especially given how the team had played in their opening match against Granada last weekend.
"The result wasn't what we wanted, but I liked our attitude," Simeone explained in his post-match press conference.
"We made things uncomfortable for them, but we couldn't find our rhythm in the final third to hurt them.
"They are a team that plays very well and enjoys long periods of possession, which was on show at all times today."
Lucas Torreira has completed a medical with Atleti, however before his signing can be made official there needs to be sales. Simeone, meanwhile, refused to give any further detail on the situation.
"I'm not even aware of that situation, I have nothing to say," he added.
"I'm only concerned with having been unable to beat our opponent today.
"Sometimes it's difficult to explain this type of match, we just couldn't generate goalscoring situations."
When quizzed on potential departures, Simeone admitted that he was worried about losing multiple players before the end of the transfer window.
"It's going to be busy and worrying," he confirmed.
"Let's hope there are no surprises for the worse, because there can always be bad surprises.
"It may be the case that we end the market with the players we have and we head to face Celta Vigo with the squad we have for the entire season."