30-year-old Danish international Nadim has been with the Super League team since January, after agreeing the switch last September.
Nadim is currently on tour in the United States with City as part of the International Champions Cup.
She scored in a win over Paris Saint-Germain on Wednesday, but hasn't been able to get as much playing time as she would hope for at the club.
"It is a fantastic club in many ways, but not for me," she told 'BBC Sport.'
"I've never felt home either in Manchester or Man City. I have made it very clear to the management that I want out, and this is something I've felt for a long time."
Nadim reached the Women's Euro 2017 final with Denmark, and she wants to think about her international career as well.
"I have to think about myself and I can't stay. It is a World Cup year, and I want to be prepared for that. I just hope the club respect me as a person and accept my transfer request. I hope that the situation is solved soon so I can concentrate on football and feeling happy."
Nadim was born in Afghanistan, but fled the country with her mother and sisters at the age of 12.
She reached a refugee camp in Denmark, which is where she began to play football.
Nadim also spent some time playing in the United States, for the Portland Thorns and Sky Blue FC.