WASHINGTON — The Obama administration has deepened its rift with its Gulf allies over the ongoing conflict in Yemen, blocking a transfer of precision munitions to Saudi Arabia because of concerns about civilian casualties that administration officials attribute to poor targeting.

Administration officials said on Tuesday that the White House had made the decision to block the sale by Raytheon of about 16,000 guided munitions kits, which upgrade so-called dumb bombs to smart bombs that can more accurately hit targets. The kits, if purchased over the life of the proposed contract, are valued around $350 million.

But administration officials said that upgrading the bombs would not help targeting if the Saudi-led coalition in Yemen did not choose its targets properly, an ongoing concern since the start of bombing campaign. This year, the United States blocked a sale of cluster munitions to Saudi Arabia because of similar concerns.

The administration’s decision is a setback for Raytheon, which officials say pushed hard for approval of the sale. Administration officials said that Raytheon’s chief executive, Thomas A. Kennedy, personally lobbied Tony Blinken, the deputy secretary of state, and also reached out to Secretary of State John Kerry and Susan Rice, the national security adviser. It was unclear if he connected with Mr. Kerry or Ms. Rice.