Osasuna have only won once in their last six games and are now just four points clear of the relegation zone with seven games to play.
However, Punal, 37, has denied that a negative feeling is sweeping through the dressing room as the end of the season approaches.
"We are not in decline," Punal told the club's official website.
"We have been beaten by several sticks by recent defeats, but the self-esteem of the team has not dropped.
"There is a sense that the streak is negative but we want to get the three points and that's it.
"We know that if we play a good game we can win."
Punal also hailed the club's fans for their unwavering support when the results have not been going in their favour.
He said: "I know our fans are there when we need them the most.
"The partnership is unconditional and when we are in deep water, it also binds to encourage other people.
"We need and will hopefully play a good match where we can enjoy and give everyone a great joy."
Sociedad, who are currently fourth and will be looking to consolidate their Champions League qualification place, look set to be without defender Ion Ansotegi after he pulled out of training with lower back pain.
Defender Alberto de la Bella could also miss out as he recovers from a tendon problem.