“There are brokers who hire people to stand in line for them — they set up tents, they sit in chairs with sleeping bags — and we don’t want a tent city that encourages brokers to resell,” Mr. Seller said. He noted that only a handful of tickets become available last-minute for any performance, and said: “We want to ensure that if anyone has perseverance, they are a beneficiary of the line. But this camping out has to stop, because it had crossed over into public nuisance.”

A visit to the theater Friday morning found about 10 people lined up hoping to buy tickets to the 8 p.m. performance; some had been there for 19 hours, with another 10 hours to go until showtime. There were no sleeping bags or tents in sight — several people said they had slept on bathroom towels or blankets — but a few people sat in folding chairs, despite the new rules. (The tickets released at the last-minute, often loosely described as “cancellations” and sold at full price, are separate from the $10 tickets that are released for each performance via digital or in-person lottery.)

On two theater chat boards, unnamed ticket holders who were planning to travel to New York to see “Hamilton” complained that they were unfairly caught up in the crackdown, and had lost their tickets to the show.