No, Christians were called cannibals because a garbled version of Eucharistic theology was circulated around the Roman world.
This classic urban legend (later becoming a slur on Jewish people in the Middle Ages) said that Christians met together for their “agape” meals only to dim the lights and eat a baby with their bare hands and drink its blood. Then the evil Christians would put out the lights entirely and have sex with random people in the dark. (They were also wicked magicians who controlled demons and disrupted temple ceremonies and decent normal magic by using the name of Chrestus, the executed criminal, to master all other magical names.) This behavior brought down the gods’ curse on humanity and caused famines and plagues. Therefore, if anything disastrous happens, decent people should kill Christians or denounce them to the government.
St. Justin Martyr’s First Apologia is written entirely with the idea of disproving this urban legend by speaking frankly about what really went on at a typical Mass, in terms that a Roman could understand.