Striker Chris Wood scored twice to take his tally to 22 league goals this season, with Alfonso Pedraza also on target, as Monk’s men maintained their promotion push.
Monk, who watched the game from the stands following a touchline ban, said: “I didn’t enjoy the first 60 minutes if I am honest. We were second best in the first half.
“We looked a little restricted, but we were playing against a very good team. It was tough for us as Birmingham were excellent in the first period.
“Our mentality is so strong to fight and defend. But in the last half hour we were excellent.
“We always looked dangerous and scored some very good goals. In the end we won comfortably and it was not from lack of a good performance from Birmingham.
“The spirit is clearly there as the team has a strong winning mentality even when we faced difficult situations.
“It was a hard game for us as I thought it was one of Birmingham’s strongest performances and they will feel a little aggrieved they didn’t capitalise upon some of their situations.”
Monk is refusing to get carried away by his side’s form.
He said: “It was only three points and no one has achieved anything. No one is guaranteed anything at the present time.”
Wood, spent six months on loan at Birmingham earlier in his career, was in devastating form as he confirmed himself as the division’s most in-form striker.
But Birmingham had every reason to feel down-hearted after producing one of their best performances this season.
Che Adams was foiled by goalkeeper Rob Green and a goal-line clearance from Kyle Bartley early in the second half as Leeds were hanging on.
Craig Gardner briefly brought Birmingham level by cancelling out Woods’ opener, but the forward soon struck again.
Zola left frustrated
He said: “I was more than disappointed. The result doesn’t reflect what happened on the pitch.
“What made the difference was that on the other side was a player who touched the ball three times and scored twice. He made a big difference.
“Maybe we made a couple of mistakes. One was down to inexperience, another we could have avoided.
“But to be honest it is very difficult for me to say anything to the team when they produce a performance like that against a team third in the league.”