Borussia Dortmund’s sports director Michael Jork has insisted Sancho will not be sold until the transfer window closes on Monday.
The United Bundesliga club are unwilling to meet the 120 120 million (m 108m) bid for the England wing, so the 20-year-old is ready to move to Germany.
It emerged this weekend that United were closing in on signing former Paris Saint-Germain striker Edinson Cavani.
Rooney believes he should face Tottenham and England frontman Kane, who will face United in the Premier League clash at Old Trafford on Sunday.
“Yaden Sancho is a top player, but I find it strange that he has preferred a replacement for Manchester United,” United’s record goal scorer Rooney told the Times on Sunday.
“Why consider paying close to 100 100 million for someone you already have? United’s Marcus Rashford and Anthony Marshall and where will Sancho’s arrival leave Mason Greenwood, who plays in the same position and is the same age?
“I put m 100 million on him instead of trying to get Harry Kane. Yes, getting Kane out of Tottenham would be difficult, maybe impossible, but United are a club that always have great players to sign. Should try and Kane is. All Gunnar Salisbury needs exactly the same as Earling Holland, who missed out on United last year – a real number nine.
“Someone like Kane or Holland or Robert Lewandowski would give Rushford and Marshall the freedom to play and move around in different areas, picking up the ball and trying to beat the men – without a score.”