Mourinho worked with Ibrahimovic at Inter Milan, and the Blues have been linked with a number of strikers in recent months.
"It is impossible. This is another thing which I don't want to feed the rumours of. He is happy at Paris. I know because we are in touch, we're friends. Zlatan is mission impossible," Mourinho told Canal+.
Ibrahimovic scored a hat trick in his side's 4-2 win against Toulouse on Sunday.