Ronaldo said, in the interview with Piers Morgan last month, he felt betrayed by the club and did not respect Ten Hag.
United then announced that the Portugal international, who rejoined the club in August 2021 after winning eight major trophies with them from 2003 to 2009, would leave immediately.
Asked if United were in the market for a new striker, Ten Hag told reporters, "Yes, but only when we find the right player.
"We do everything that is in our power, so I do research on every opportunity that comes. We do everything we can if that opportunity will be there.
"I cannot give comment on specific players, I will never do. I've told you before, in the summer as well, when you talked about a lot of players. Each player is under contract and I respect that, but we make sure we are working in the background to get the right players in."
United next host second-tier Burnley in the EFL Cup on December 21st, after the World Cup in Qatar.
