The Brazilian playmaker joined the Red Devils from Shakhtar Donetsk last month for a fee reported to be in excess of £50million, but is yet to feature for United in pre-season after World Cup duty with the Selecao.
However, the Portuguese has been informed that he will have to let one of his existing central defenders go, in order to make a move for Maguire.
Mourinho was speaking to the media in Los Angeles before his side's pre-season friendly against AC Milan on Thursday. But I think it's how do you get the best out of him?
"I told already", he answered when asked what it will take for him to be happy with the midfielder.
The 25-year-old also helped France win the 2018 World Cup this summer - scoring in the final against Croatia.
Mourinho: Pogba thrived due to World Cup environment
The same story is suggesting that Mourinho remains a massive admirer of Ivan Perisic but that Rebic could offer a cheaper alternative with United becoming increasingly frustrated with their summer transfer business.
Martial's relationship with Jose Mourinho broke down significantly last season and the likes of Chelsea and Juventus are expressing a strong interest in the Frenchman ahead of the 2018/19 campaign.
"The first match of the season is against Leicester and the second one is against Brighton", Mourinho said.
"So I think it's the flawless environment for a talented player like him to focus, to fully focus on the job".
He would like to bring two more players to Old Trafford ahead of the new season but accepts it may be hard.
"If our players are interesting a lot of clubs it is because we are recruiting well and doing good work".More news: US Ready to Make ‘Real Deal’ with Iran
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