Blues have taken only one point from a possible nine since their shock Wembley triumph over Arsenal last month. They slid into the bottom three of the Barclays Premier League after the 2-1 defeat at Wigan 12 days ago.
But McLeish will demand a positive response after the international break, starting with Saturday's home clash against Bolton.
The Blues boss said: "I have spoken to a lot of people in the last fortnight and it is clear there is often a reaction after a huge game like that cup final.
"It's not unique because as a club you have to dig deep into the reserves of energy in your players. But the fact is we lost momentum and we need to get it back. We need to hit the ground running on Saturday."
He added: "We'll be putting pressure on every player to do that, including those coming back from international duty.
"Never mind 'your country needs you' - it's a case of 'your club needs you'."
Source: PA
Source: PA