Club president Giovanni Cobolli Gigli sought to ease the unrest by promising to boost the squad in the close season.
"Our directors are working in harmony with Ranieri to try to reinforce a team that did well until a few weeks ago, but then in some situations showed itself to be inferior to opponents," he told Rai television.
Serie A leaders Inter Milan are seemingly out of reach, holding a 10-point advantage with six matches to go and AC Milan have pulled level on points with Juve to move into second.
The Turin outfit are also at the centre of a storm caused by their fans racially abusing Inter Milan's Mario Balotelli in Saturday's 1-1 draw.
Juve fans again sang abusive chants about the 18-year-old striker on Wednesday even though the team has been ordered to play their next home league match against Lecce on May 3 behind closed doors for what happened last weekend.
Although the insults were not of a racist nature this time, the incident will not help Juve's appeal against the stadium ban.
NOT QUITTING
Ranieri said he was not throwing in the towel amid growing speculation about his future.
"I'm not going to quit. Now we must react immediately," the coach was quoted as saying by La Gazzetta dello Sport.
"It (the fans' protests) does not please us. But we're fighting, doing our best. We have to know how to accept both compliments and criticism."
Inter are looking to move towards a fourth consecutive league title with a win at Napoli on Sunday, while Milan welcome seventh-placed Palermo to the San Siro earlier in the day.
Sixth-placed AS Roma visit fifth-placed Fiorentina on Saturday in an important match in the race for Italy's fourth Champions League slot.
Victory for Roma would bring them level with Fiorentina on 55 points. Surprise package Genoa, who are two points further ahead in fourth, visit struggling Bologna on Sunday.
