The Spain midfielder's season is over due to a knee injury.
Guardiola said: "He had surgery on his ACL and some meniscus, and next season he will be here - but this season is over.
"We got the worst (news), but it is what it is. At this level unfortunately this happens. We are there to support him and hopefully he has a good recovery step by step, and move forward.
"Everybody knows how happy our opponents are, because they have the mindset that Rodri is fundamental to our process, but what can we do? Complain? We have to find as solution as a team, and use important players. We have to move forward and move on.
"When we lose, it will be because we don't find a way, but I am optimistic that we will find a way. The team is good, and together and we will try to do it."