The pair had a row during Chelsea's Champions League win against Maccabi Tel Aviv on Tuesday.
But although boss Mourinho attempted to play it down afterwards, he renewed his criticism of his misfiring striker today.
"In the game I told him - from a distance - that I was not happy with the movement he did," said Mourinho.
"He told me also a few nice words from where he was, and nothing happened. Nothing happened at half time.
"He's not reading the game properly. That was my opinion. As a striker, he must read.
"You have to play not when you have the ball, but when others have the ball. You have to anticipate and read the game faster."
Costa scored his first goal in seven last week but has only managed six more in the last 10 months.
"You're not on fire again just because you've scored a goal against Norwich," said Mourinho.
Mourinho also had a dig back at former striker Didier Drogba who has claimed in his new book that the struggling champions lack leaders right now.
He said: "When you speak because you want to sell books, I don't read it. This was not an interview. It was to sell books. It doesn't disappoint me. It was just the reality. I can analyse Didier's interview with pleasure, but not Didier selling books."
Chelsea face Tottenham on Sunday, desperate to avoid a repeat of their 5-3 hammering at White Hart Lane last season.
Spurs are currently 10 points and 10 places ahead of their London rivals.
But Mourinho reckons Spurs boss Mauricio Pochettino has it easy as there is no pressure on them.
He said: "Nobody speaks about them as title contenders like they speak about Manchester City, United, this and that. They lose a couple of matches and nothing happens.
"They are in the Europa League, in the group phase, and no one cares about that at that stage. They go smoothly step by step, build a team, new players, give conditions for the young players to develop. They have good conditions to do very good work."
