The returning manager highlights the importance of finishing top of the table in England, while also hoping to help striker Fernando Torres to recapture his old form.
The Blues struggled to impose themselves on the race for domestic glory last season, but Mourinho has indicated that it will be prioritized above other competitions in 2013-14.
"The most important thing in football is to be the best team in the season and try to win your domestic league," Mourinho told BBC Sport. "In our case, it's the most important league in Europe, so we have to try and be the best team and win the Premier League."
Despite the Blues' triumph in the Europa League last season, Mourinho is keen to avoid a feeling among his squad that they can acceptably settle for anything less than the top table of the Champions League.
"I don't want to win the Europa League," Mourinho said. "It would be a big disappointment for me. I don't want my players to feel the Europa League is our competition."
"[The Champions League] is the only European competition we have to play, and that's the European competition [in which] we have to give our best."
Mourinho also declared that age or nationality will be no object to any of his players earning a place in his team if their form is good enough, mentioning Fernando Torres in particular a player he will nurture to build confidence.
"I don't care about the passport, I don't care about the date of their birth, I just care about performance," Mourinho said. "If they are better than the young guys, then they play. If the young guys are better than them, they don't play.
"But the way they are working is amazing. These guys, they know they have to give everything and don't expect that status chooses the lineup.
"Good players in big clubs, they are always under this pressure. The only thing I can promise is that I give everything to my players and I try my best to perform the best I can. [Torres] will get from me that support that a striker needs to feel more confident but, at the end of the day, it's up to them and is their responsibility. Fernando has to cope with that."