SAN FRANCISCO — A few days after Uber went public in May and its stock fell into a tailspin, the ride-hailing company’s chief executive, Dara Khosrowshahi, sent a rallying message to employees.

“There is one simple way for us to succeed — focus on the work at hand and execute against our plans effectively,” Mr. Khosrowshahi, 50, wrote to staff in a May 13 email. “We simply would not be here without you.”

Since then, Mr. Khosrowshahi’s message has steadily become tougher.

Faced with questions about whether Uber can make money and a souring environment for unprofitable tech firms, Mr. Khosrowshahi has laid off more than 1,000 workers in three rounds of job cuts. He has ousted some top executives, and board members have left. And in recent emails to employees, he has said Uber’s teams are “too big,” are producing “mediocre results” and that the company “needs to get its edge back.”

Inside Uber, managers are quibbling over expense reports and tighter budgets, according to four current and former employees who declined to be named because they were not authorized to speak publicly. Executives have asked employees to suggest perks they are willing to give up. Some workers have been told they need to stretch themselves even thinner in the wake of layoffs.