WASHINGTON — A senior administration official said on Friday that the United States had repeatedly warned Huawei, one of China’s flagship technology firms, about violating American sanctions on Iran before the arrest Saturday of one of its top executives.

“We’ve warned them for quite some time of violating the Iranian sanctions,” Larry Kudlow, director of the White House’s National Economic Council, said on CNBC on Friday. “We have these sanctions on Iran, it runs against our policy, why shouldn’t we enforce that?”

The arrest, which was executed by Canadian authorities in Vancouver, has threatened to further complicate the trade conflict between the United States and China as they try to resolve their differences during a 90-day truce.

Mr. Kudlow tried to play down any impact on those discussions, saying that the arrest of Meng Wanzhou, Huawei’s chief financial officer, was a separate matter that should have no bearing on economic negotiations. President Trump and the Chinese leader, Xi Jinping, agreed last Saturday to the 90-day trade truce, during which time there would be no additional tariffs as the two sides talk.