Gossip emerging from France had claimed that Pogba had grown so unhappy with Mourinho about the ongoing debate over his position that he 'regrets' re-signing with his former club.
The 24-year-old was substituted early during the loss against Tottenham last month after an animated touchline discussion with the boss. He was then dropped for the subsequent game against Huddersfield and looked to be carrying an injury during an ineffective performance against Newcastle last weekend, although Mourinho later denied there was any problem.
Mourinho called the rumours of a fall out 'a lot of lies' when he addressed the media at a press conference ahead of Saturday's FA Cup tie against Huddersfield.
"I can speak on Paul's behalf without any problems, and Paul accepts that he's not being playing well in the last few matches," the Portuguese explained (ManUtd.com).
"I don't want to speak to you about my conversations with my players. I don't have to tell you anything about it. It's my problem, it's the player's problem," he added.
"It's a big lie that our relationship is not good, a big lie that we don't communicate, a big lie that we don't agree with his positions and his involvement in the dynamic of the team."
Mourinho confirmed that Pogba will be in the United line-up as they face Huddersfield for a third time this season, and for the second time in as many weeks, further commenting that the player's lengthy injury layoff earlier in the campaign is likely to have had a continued impact.
"He had a big injury. The decision was not to do [surgery] and to go with conservative treatment which went very, very well. Everybody was happy with the way things went," the manager said.
"He was playing phenomenal before that, he played phenomenal after that. He had a red card against Arsenal, probably in his best match of the season and in his and the team's best moment. He was out for a long, long time and, in this moment, he's not playing well. Period."