Kenya were held to a 0-0 draw by Burundi in regulation time until Whyvonne Isuza came to the rescue with a 97th minute extra time goal at Moi Stadium in Kisumu on Thursday.
The not-so-convincing display by the home side left the Belgian tactician seething at the lethargic performance from his players.
"I was very disappointed with our performance in the first half. We started slowly but came back in the second half. We were very lucky not to concede a goal in the first half," Put revealed in a post-match interview.
"I was surprised that we found ourselves in this situation with all the quality (we have). I was disappointed but I must admit that Burundi is a good side."
Stars will now meet the winner between Zanzibar and defending champions Uganda in the final on Sunday at Kenyatta Stadium in Machakos County.
Uganda and Zanzibar will square it out in the second semi-final on Friday.