KABUL, Afghanistan — The Afghan government said on Tuesday that it would not take part in negotiations with Taliban unless a cease-fire had first held for at least a month, a demand that is likely to face resistance from the insurgents and complicate the revival of peace efforts that were upended by President Trump.

Hamdullah Mohib, the Afghan president’s national security adviser, told a news conference in the capital, Kabul, that the government saw a cease-fire as a test of whether the leaders negotiating on behalf of the Taliban still had the power to order an end to fighting, something that rising levels of violence during the group’s talks with the United States had led it to doubt.

“In our previous peace plan, we had no preconditions,” Mr. Mohib said. “But in the past year a lot has happened, and we have come to the conclusion that the Taliban are not united and they don’t have control of the fighting . If we are going to give the Taliban the privilege of peace negotiations, they need to prove how much control they have over their commanders and fighters.”

The Taliban have long refused to meet the Afghan government for direct negotiations even without preconditions, saying they would agree only to government representation in broader Afghan negotiations after the United States has announced the withdrawal of its troops from the country.