The former US Open champion missed most of last season after having surgeries on her ankle and both wrists.
Raducanu was looking to build on her performance at Indian Wells, where she played well but lost in the third round to world number two Aryna Sabalenka last week.
She received a wildcard into the main draw at the Miami Open and was scheduled to face China's Wang Xiyu in their first round match on Tuesday.
"I have been experiencing lower back pain and at this stage of my return to competition I don't want to risk anything happening," Raducanu said in a statement issued late on Monday by tournament organisers.
"I really tried my best to be ready and I'm sad to be pulling out of Miami as it’s a cool tournament but wish the event all the best."
Raducanu, who in 2021 became the first qualifier to win the US Open, is scheduled to play in Britain's Billie Jean King Cup tie against France next month.
