McCall held talks with his former club, where he ended his playing career and began coaching, but decided against a move to npower League One.
McCall, who signed a new two-year contract in March, said: "It has been a really difficult last few days. As most people probably know, I spent five great years at Sheffield United.
"I was grateful to the board for allowing me to speak to them but I went with an open mind. I had no desire to leave Motherwell after enjoying two-and-a-half great years at the club.
"There is no doubt Sheffield United are a fantastic club but, after careful consideration and deliberation, I am more than happy to continue my current role at Fir Park.
"I have built up a tremendous feeling for Motherwell, the people who work at the club and the supporters. It would take something really special to tempt me away."