The 43-year-old brought an end to his long-running association with the Red Devils last summer following the exit of Louis van Gaal.
Giggs was initially expected to work alongside Mourinho and help with a smooth transition after spending two seasons under the Van Gaal regime, but the Welshman has revealed that it was never an option to stick around at Old Trafford, even if he had wanted to.
"There was no offer from Jose Mourinho. No offer. It was my choice to go," he told Manchester Evening News. "As soon as Louis was going I had made my decision to go.
"I had done two years and I wanted to do three years under Louis. It didn't happen. That was my plan, to do my three years and see what happened after that.
"Unfortunately, that was cut short. It happens. That's football. But I didn't really feel I could go on at the club in any other capacity apart from manager."