Celtic have reiterated their desire to keep hold of Croatian centre-back Jozo Simunovic.
"We want to keep him here," said Kennedy.
"He's a big player for us now and he's shown that in the last couple of Champions League games.
"He's a top player and we want to keep our best players.
"He's one we wanted to bring in to improve the team. He's been terrific and is a fantastic player to work with.
"Everything he does is for his career and for the good of this club. He is in a good position at the moment so it is just about maintaining that for him.
"He had a long period out last year but he has looked strong since he came back.
"He's got the height, the strength, the speed and technically he's very good. On top of that, he's got a fantastic attitude. Nowadays proper centre-backs are very hard to come by."
Kennedy likened Simunovic to Dutch centre-half Virgil van Dijk, who spent two seasons with Celtic, before moving to Southampton where he is commanding the attention of Manchester City, Manchester United, Liverpool and Everton.
"You look at Virgil van Dijk, who all the top teams are now chasing," Kennedy added.
"Jozo is certainly of that ilk. He ticks a lot of boxes. You get a lot of centre-backs now who don't really want to defend and that becomes a problem for you when you are put under pressure, but he's one that likes to put his head in. He makes tackles, but he can play when need be.
"Van Dijk's a top player. Even when I worked with him here, I don't think people appreciated what he was all about.
"Jozo's still got a little bit to go in terms of reaching that level but he certainly has it in his locker to keep progressing the way he is, and who knows?"