Catalysis of the PEP-dependent, phosphoryl transfer-driven transport of substances across a membrane. The transport happens by catalysis of the reaction: protein N-phosphohistidine + N-acetyl-mannosamine(out) = protein histidine +N-acetyl- mannosamine-6-phosphate(in).
protein-N(PI)-phosphohistidine-N-acetyl-mannosamine phosphotransferase system transporter activity