Fabregas, 33, played one season under Guardiola at the Camp Nou before the manager left in the summer of 2012 to take a sabbatical.
"No, no, with Pep nothing at all," Fabregas told Radio Cataluna when asked if he has been in contact with Guardiola since.
"I don't know if the disappointment with Pep is mutual. Things happened, but I prefer not to talk about it. Pep was my idol since I was a child. It is him I have learned the most, perhaps, since I was four until now."
Fabregas does remain in contact with Tottenham manager Mourinho.
He played under Mourinho for 19 months at Stamford Bridge before the manager was dismissed in December 2015.
"Mourinho inspired me the most when I left Barca," he said.
"He told me that we had had our issues on the pitch when he was at Chelsea and I was at Arsenal and then when he was coaching at Real Madrid and I was at Barcelona, but that for him, it all ended there. We turned the page.
"He told me about his project. I had to go where I thought I would do best, the decision was mine and it didn't depend on what people said. I prioritised the professional [aspect], and today I still write to him and I consider him a friend.
"He helped me a lot at a difficult time in my career and perhaps I played one of my best seasons with him."
Fabregas won the Copa del Rey with Barca under Guardiola while with Mourinho he claimed the Premier League title and the Carabao Cup during the 2014-15 season.