The Blues, who exited the last-16 to Paris St Germain on away goals on Wednesday, are five points clear of Manchester City with a game in hand.
Mourinho's men have 11 games to play, beginning with Sunday's match at home to Southampton.
"We have 11 matches to play in the Premier League
We want to be champions, to win the Premier League, but also to be back in the Champions League, to be head of group," said Mourinho.
"We cannot promise that (we can) win every game, we cannot promise that we (can) win the Premier League, but we are optimistic.
"You have to be optimistic to succeed
Be optimistic
Believe in yourself."
Following the 2-2 draw at Stamford Bridge and 3-3 exit on away goals, Mourinho insisted he would take time to analyse the performance
He declined to reveal the content of his debrief with his squad, which took place on Thursday.
"I reflect with the players not with you
I don't have to say," he added.
"I had a meeting with the players, I'm working for the future and I don't have to share with you."
Mourinho refused to respond to Zlatan Ibrahimovic - the PSG striker who was sent off in the second half as the referee was surrounded by Chelsea players - branding the Blues "babies".
"I keep saying to you and to many of you that I don't comment on what the others say
I have my own opinion about things," Mourinho added.
"My point is that if you want to speak about Champions League you have to go to (Arsenal manager Arsene) Wenger or to (City boss Manuel) Pellegrino (sic).
"I don't want to go back
I want to go forward
I think they will cope with the pressure of playing Southampton."
Chelsea skipper John Terry defended the actions of the Blues players after the Ibrahimovic incident
So did Mourinho.
"If they surround the referee, we are charged, we have to pay a fine
If we do that the players play the fine," the Portuguese said.
"We were charged once (this season)
We pay for that."
On criticism of Chelsea's players from television pundits Jamie Carragher and Graeme Souness, Mourinho said: "The world is a bit strange, maybe because of diet and the quality of product we are eating, memories are getting shorter
"When Jamie Carragher and Graeme Souness are speaking about it it's because they're having a problem for sure.
"Jamie stopped to play a couple of years ago and in two years he forgot everything on the pitch."
On Souness, who worked at Benfica prior to Mourinho working there, the Blues boss said: "I know a lot about him
I know so much about him."
He then kept his counsel.
Midfielder John Obi Mikel (knee) remains out, but Mourinho has no other fitness concerns.
He said: "Everybody wants to play."
Source : PA
Source: PA