Reports have emerged that Spurs players believe they are regressing under the Portuguese while defender Danny Rose is said to have clashed with him after being left out of the matchday squad.
But England midfielder Dier has denied the claims and says any unhappiness only stems from frustrating results on the pitch.
“Any club, when results aren’t going well, is not a happy atmosphere,” he said. “But it definitely isn’t a negative atmosphere.
“I don’t feel anything along those lines personally and I think everybody has been training very well, training hard, enjoying themselves in the same way as always.”
When asked about the training methods, which were described in Wednesday’s article in the Sun newspaper as “like lower-league sessions”, Dier was quick to defend Mourinho and his staff.
“Who is saying that? Maybe you lads know — I don’t,” he said. “But personally I have enjoyed it. I enjoy doing new things.”
Club captain Hugo Lloris also dismissed such claims, insisting everything was “positive”.
The Frenchman, who made his first appearance under Mourinho in the 2-1 win over Norwich following a three-month injury lay-off, said: “I can tell you that it’s completely wrong.
“The atmosphere is great, we can feel all the players involved and ready to fight for the club, the new manager and his staff.”
After a bumpy spell, Spurs got back on track against Norwich on Wednesday in what could be Christian Eriksen’s final appearance in front of Tottenham’s home fans.
Eriksen is widely expected to leave before the January transfer window closes, with Inter Milan keen on taking him to Italy.
