About 60 of the 200 demonstrators, who gathered in Dover to mark the six months since the restart of live animal exports through the port, were demanding to lay bunches of flowers in front of the Eastern Docks, but they were denied permission by Kent police "for safety reasons".
A police spokesman, Mark Pugash, said: "We can't just let lots of people go across the road. This is to prevent any accidents and danger to both motorists and the protesters themselves."
No arrests were made but furious protesters claimed they were being persecuted and that they had a right to lay the flowers.
One said: "If they just let us lay these flowers it would all be over in a couple of minutes. The police provide escorts for the lorries carrying these animals but they won't escort us across the road."
Earlier, a cavalcade of more than 40 vehicles, organised by Kent Action Against Live Exports, had travelled around three lairages where animals are kept at the villages of Capel, Petham and Shepherdswell. The tour passed off peacefully although the protesters angrily sounded their horns when a lorry filled with livestock left the lairage at Petham as they approached.
Six lorries loaded with sheep and calves passed through Dover at 9.30am, one of two cargoes expected through the port yesterday.
The next convoy was expected at 12.30pm, and the planned memorial service was not allowed to go ahead.
After negotiations with police, demonstrators were finally allowed to go in pairs to lay flowers outside Dover Eastern Docks.
Most of the protesters were unhappy with the compromise and responded by chanting: "Just like Noah's Ark - two by two."
Among those waiting to lay flowers were Joyce Wells and Eileen Chambers, both 79 and both from Herne Bay. Mrs Wells said: "The way the police are treating us is as if we are criminals."
The police said that to hold up traffic for just a few minutes would cause "major disruption" in what is a busy part of town. But few of the protesters were happy with the compromise.
Jo Le Mesurier, widow of the Dad's Army actor John Le Mesurier, and one of the second pair allowed to lay flowers, said: "This is farcical. Why don't they let us go through in one fell swoop and get it over with? At this rate it will take all morning."
Mr Pugash said: "If we held up the traffic even for a few minutes we would have major disruption so we offered the compromise of taking them over two by two.
"Initially we said they could gather up the flowers in groups and then one or two of them could place them on the roundabout in what is a busy part of the town, and which they accepted."Reuse content