The fashion designer - who is expecting her second child with fiance Eric Johnson - was reportedly planning to pay up to $12 million for the Beverly Hills home but after Sharon left a candle burning and it caused a fire, Jessica has had second thoughts.
A source told RadarOnline: "When Jessica and Eric heard about the fire they were as equally as disappointed as the Osbournes.
"They were planning on making an offer on the mansion somewhere in the region of $12 million, because they felt it was the perfect family home.
"Now, they're going to have to assess the damage before committing, even though they heard it is pretty minimal.
"Jessica does have her sights set on the property but she is now looking elsewhere.
"She's also a believer in fate and is wondering if the fire was a sign that she shouldn't buy it and wait for something else to come on the market.
"It's a shame for Sharon and Ozzy - they were ready to sell."
Sharon previously revealed she and Ozzy attempted to put out the blaze themselves before the fire brigade arrived.
She explained how Ozzy - who had surgery on his hand the previous day - tried to use the cast on his arm to help put out the fire, adding: "I go into the kitchen to get water and throw the water on it, with the doors open and the water it erupted! It erupted, Ozzy's hair from here to here, gone.
"And we are like two idiots, it was like The Three Stooges. Everything you are not meant to do - go to bed with candles alight, open the doors and put water on - we did it all."