The England striker reacted slowly to an Aaron Lennon shot which rebounded off a post in the first half and failed to beat Robert Green from six yards in the second period as Spurs had to settle for a goalless draw against their local rivals.
"Jermain was up half the night due to a family bereavement," Redknapp said.
"I wasn't sure whether to play him but he wanted to.
"He had some good chances, the little fella, and he normally scores them but it was just one of those days. It wasn't through a lack of effort.
"He was bright, he was sharp he just couldn't score but that's football. That's how it goes, another day he'll go and bang a couple in.
"The two goals he got at Wolves, he had no right to score them. They weren't even half chances."