The ad, created by Lowe, features the creature talking about how germs such as e-coli and staphylococcus used to be in control and were able to harm humans. A close-up of the germ shows its large mouth and teeth before he shouts: "But now they hunt us down!"
The monster then becomes animated, lunging and spitting at the camera, before saying: "We've become their prey. So here we are, cornered. We can almost hear the finger on the trigger. The finger of death."
The product then appears on the screen and the voiceover said: "Domestos spray. Millions of germs will die."
Nineteen of the 27 viewers who complained said that their children, aged between 18 months and five years old, were frightened by the ad.
Even though the ad was given no restriction by the Broadcast Advertising Clearance Centre, the advertiser decided to schedule the ad away from children's programmes at the last minute, however three spots remained scheduled during these programmes.
The BACC said it found it difficult to gauge how young children would react badly to the animated character in the ad, saying that Harry Potter and Roald Dahl books and films often contained similar sorts of characters, which did not frighten children.
The ASA said: "We welcomed the advertiser's attempt to schedule the advertisement sensitively.
"We considered, however, that the complains we received showed the ad was likely to frighten some young viewers and should therefore have carried a scheduling restriction to ensure it did not appear in or around programmes made for or specifically targeted at children."
The ad will now not be shown again in or around children's programmes.
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