The 29-year-old takes on his former club in a crucial game at Anfield, with the Blues requiring a win to close the gap at the top of the table to two points.
Mourinho has already declared that "if we have to play the kids, we play the kids" when referring to his team selection with Wednesday's Champions League semi-final second leg against Atletico Madrid in mind but Johnson has urged his team-mates to ignore the 51-year-old's comments.
|7/1||Liverpool are 7/1 with William Hill to beat Chelsea 2-1|
"And if we play like we did against Manchester City [in a 3-2 win on April 13], we can beat anyone.
"I don't see much of it, if I'm being honest, but I can just laugh it off because that is what they do.
"Their situation is different at the minute, as they are in-between Champions League games. We don't know what their priority will be or what Mourinho is thinking. You try to ignore all that."
With three league games remaining, Liverpool are five points clear of Chelsea – while Manchester City are a further point back and have a game in hand.
But Johnson declared: "We are keeping professional at all times.
"At the minute, we haven't got anything to be excited about, have we? If we lose the next three games, everything we have done over the last couple of months will be wasted.
"There are no given three points at this stage. We are going to have to earn every single one if we want to achieve what we are close to. Beating Norwich was even more important than beating City."