East Sussex Fire and Rescue Service said it was called at 18:39 BST and two fire engines were sent to the scene to assist.
The i360 pod was carrying a private party, including a heavily pregnant woman, who boarded the pod at about 17:00.
It was lowered to the ground about two hours later.
The BAi360 Twitter account said: "Our engineers are resolving the problem & expect it to be working normally soon."
A local firm of building and quantity surveyors, MacConvilles, tweeted saying: "Our Director is enjoying the hospitality of the #i360. Technical hitch has halted ride but help is on its way!"
Tim Jones, one of the party organisers, said: "We weren't very high up when we juddered to a halt and we were told by staff to move to one side of the pod to 'recalibrate the weight' - which made some people a bit nervous.
"It was an interesting experience, and quite ironic as the party was organised by four local businesses who wanted to come together to celebrate the tower's opening."
"Only two interactions were made over the two hours and they kept pretty quiet about the free bar and the emergency toilet until we were nearly on the ground," he added.
A "technical hitch" has been blamed for leaving 180 passengers stuck on British Airways's i360 attraction in Brighton.