The action was taken to protest against Peter Jolly's Circus, which held shows featuring animals in a Big Top near Maesbury Road on the outskirts of the town.
Campaigners waved placards and some of them stood in the central reservation of the A483 for several hours to make their feelings known in an effort to get drivers' support.
They said wild animals are not suited to being kept in captivity for "entertainment".
Dozens of police were called in to keep the peace and to keep the A483 safe.
The circus had three zebras, five reindeer, a camel, llamas, a parrot and miniature Zebu Indian cattle plus other animals that performed at the site for a fortnight.
A spokesman from West Mercia Police was asked about the protest on Saturday but failed to respond.
Back in June the owners of Mr Jolly's Circus hit back at Shropshire protestors who called for their shows to be boycotted.
More than 1,700 people signed a petition urging Newport Rugby Club to change their mind in letting the Peter Jolly's Circus perform in their grounds.
But, in a statement, the circus said the controversy has been greatly exaggerated by people, including a number of anti-circus groups. The statement said: "We are constantly accused of cruelty and neglect to our animals by these animal rights organisations, who thrive on spouting propaganda to the general public by the medium of press, and unfortunately people are misled.
"These people have never actually seen for themselves, they only believe what they are told. We have held our licence to travel with performing wild animals for four consecutive years and during this time we have had three inspections by Defra, two announced and one unannounced.
"We also have to have four inspections per year by independent vets making a total of seven inspections per year."
Peter Jolly's Circus, which was today starting a run of shows at Plas Madoc, near Wrexham, said it has not used lions in its act for several years.