The former Spurs striker expects the Portuguese to spend in summer transfer window.
Berba says Mourinho cannot be judge on this season, adding that the team left behind by Pochettino had gone off the boil.
The former Spurs striker believes the Portuguese Mourinho has to be given more time to work with the current crop of players left behind by Mauricio Pochettino, and at least one transfer window would be needed to start remoulding the Lilywhites squad.
The Bulgarian told Betfair: “Things had gone sour under Mauricio Pochettino, anybody could see that, and I thought Jose Mourinho was a good choice to replace him.
“Tottenham haven’t gone backwards. Any head coach deserves a full season to bring in his players and implement his philosophy.
“Spurs are going through a difficult period, but Mourinho should be judged on next season at the club.”
The former United superstar added: “Players take time to adjust to a new manager, especially when it’s one with a different style to his predecessor.
“Occasionally, I get the feeling that some players are not playing for the team, and that they are trying to take the glory for themselves. That can ruin scoring chances.
“When he’s back, Spurs should try to release Son quicker on the counter-attack.
“These small details make all the difference in football.”
Berbatov scored a total of 46 goals and registered 24 assists in 102 games for Spurs, spending two seasons at the club before securing a move to Manchester United.