A West Midlands Police spokesperson said officers were still sent to pickets but did not explain why they reduced the number while the city council said it was warned of the move just hours beforehand.
The classroom, at the Lonsdale Community Centre, is decorated with Romanian flags and maps.Organiser Andreea Salvage said the school gave the children "a sense of belonging".
"We are now at the second generation of migrant children," she said."I think it's important to teach them to understand what Romania is because, for them, it is something totally foreign."Hull's Romanian population was 3,602.
Ms Salvage, who moved to the UK from Romania in 2007, said she thinks the number has increased significantly since then.She said each school session focussed on a topic such as Romanian history or national holidays.
"We try to do themes for each week," she said.
"For example, last week we had an election. We had an election here in the UK, and we had an election for the Romanian presidential election."They've either moved away, or sadly one died, and we've had a few injuries.
"We've gone down to very low numbers and you need a minimum number to be able to put on a decent show. We're struggling."Mr Ord, who has been with the group for 50 years, said at least half a dozen new members were needed to help its survival.
There are currently eight, but there were 20 in its prime.Mr Ord urged people to come and try out Morris dancing with friends.