The Seville-based club are currently four points off the top six following a run of just one win in their last six La Liga matches.
They will be aiming to halt that slide when they face Celta Vigo tomorrow and Perez knows the team carry their European fate in their own hands, especially as they still have to play three teams battling relegation.
"We depend on ourselves," he said on the club's website.
"The fixture list is a little messed up, with teams to come below us. That makes things difficult.
"But we're not relying on anyone else and we want to win a European place, as we deserve to.
"We are aware that in football there are ups and downs during the season and we have not performed as we would have wanted to lately.
"But we want to achieve our second goal of the season, we're professionals and you have to know what the target is.
"The first aim was to stay up, we'd done that. Europe is a dream, we have to stay strong to achieve it."
While Betis are fighting it out at the right end of the table, Celta have a battle of their own to deal with in the bottom three.
Defeat against Atletico Madrid in midweek has left Abel Resino's men two points from safety, having played a game more than the teams around them.
Indeed, they could be at the foot of the table if results go against them this weekend and midfielder Natxo Insa knows their current situation is precarious.
"The margin for error is zero," he told Marca.
"The team know this and are determined to make the most of this chance because it's our last shot."
Injuries will not help Celta's cause, however. Mario Bermejo tore his anterior cruciate ligament against Atletico and is now facing at least six months on the sidelines, while striker Park Ju-Young will miss the rest of the season with a broken feet.
With Hugo Mallo (knee) and Sergio Alvarez (shoulder) already long-term absentees, Insa is hoping the team can rise above their recent bad luck.
"Hopefully this situation will make us stronger," he said. "When dirt flies at you from all sides, you have to try and keep your head up and breathe."