The Scotland defender is believed to have held talks over a return to Tynecastle after Ipswich agreed to let him leave Portman Road this summer so that he can be closer to his daughter in Edinburgh.
But Cathro insisted there would be no official transfer business until the end of the season.
“He is a player I know and I am aware of the speculation and the intensity surrounding it just now and there are reasons for that,” he said. “There will be no comment on any of that until the end of the season.”
Cathro signed nine players in January but his side have lost a grip on a top-four place and trail St Johnstone by six points with three games left of the Ladbrokes Premiership season.
And he expects a more manageable transfer process during the summer.
“I think four players will join us,” he said. “The summer window is very different to the January window, partly because you have more time.
“We are not a club that is in the position in the market to have transfer fees so that determines it is very difficult in January and significantly easier in the summer.
“Every bit of business you do at the end of the season is simpler. The January window is a rushed one, partly because it’s shorter, the stage of the season - you are doing business whilst you are competing as well.
“It will be completely different, we will have time to prepare these things. I arrived here on December 6, 25 days before the window opened, of course it was rushed. Now it’s not.
“We have lived through things and learned things which point us in a very, very clear direction. I know exactly what we are going to bring and exactly what I want the squad and team to look like come the first competitive game.”
Cathro takes his team to face Rangers on Saturday six months after making his managerial debut at Ibrox. The 30-year-old has since won six times in 23 matches but he feels he will take valuable lessons from a difficult baptism.
“A lot of things have happened,” he said. “The biggest thing and most important thing, I know exactly what the team is going to be like.
“There have been some lessons in order to figure some of those things out and adjust some things, all the natural things that a team lives through.”