Iheanacho struck the Foxes' goal in the 2-1 loss.
"It's absolutely a tough one [to take]," Iheanacho told LCFC TV. "We need to do more. It's not good enough from us.
"We just need to get back and work on training. We got a goal back and we got a couple of chances, but unfortunately, we lost.
"We need to do more and get back to winning ways. In the next game, we need to fight and get the three points.
"We did a bit more in the second half, but we need to do more if we [want] to compete. We have six games left, so we need to compete.
"We need to get our mentality right, to fight until the end."