Speaking at a press conference in Los Angeles, Mourinho said it's "possible" that Ibrahimovic signs a new deal at United and declared, according to BBC Sport: "If the decision is to stay and wait until December - he can't be back until then - why not wait? We are speaking and changing ideas."
Mourinho added: "We wanted to let him make a decision - space and time to think and decide. He didn't want to hide behind an amazing injury. That would be easy. He was not happy in the way he finished the season. He made the challenge for himself to want to keep playing at the highest level. We opened the door for him to recover with our people and be one of us. It is Mr. (Ed) Woodward and Zlatan's agent who will deal with it."
Ibrahimovic joined United on a free transfer and inked a one-year contract with the option of a second season. Mourinho confirmed in November that the Red Devils would take up the option, but the Swedish striker was released in June after suffering a knee injury during the semi-finals of the Europa League that required surgery. He is recovering at the club's training ground.
After meeting his agent, Mino Raiola, Ibrahimovic told photographers to expect a "huge" announcement soon, according to ESPN's Rob Dawson.
Ibrahimovic tallied 17 goals and five assists in the Premier League last season, and was at the heart of United's conquest of the Europa League, notching five goals and three assists.