He is now set to make his Scotland debut after he is named in Wednesday's squad for matches against Costa Rica at home and Hungary away.
"I had this situation with two or three players, discussing the opportunity that they might be able to come and play for Scotland".
When asked whether he was surprised at how well McTominay had taken to regular first-team football, Mourinho said: "I think [it is a] effect of his profile as a boy and I think people around him are the right people, I think".
"Who will I support in the World Cup qualifiers?"
And Mourinho fuelled the fire of the worldwide allegiance debate last month when he said Scotland should pick McTominay "because it looks like England is missing him".
"Maybe I felt that a little bit - you have to do something in the game, you have to create, you have to score, you have to show you're a good passer".
McTominay has emerged as a a surprise key player for United in recent months, earning the trust of Jose Mourinho after breaking into the first team.
"He realises the weight of playing for England and working every summer - he doesn't want that".
"It would have been easy, financially, to go in the England side and if you're in the Manchester United squad there's a good chance you'll get called up by England". I'm sure England were desperate for him as well, with the World Cup coming up in the summer.
Speaking last month, Mourinho said: "I gave him my advice, but I think the parents' advice is more important than mine".
"It's been a tricky season for us, and I think getting to the end of the season and getting into the top six and then re-evaluating in the summer is my main priority".