A day after President Trump backed away from further military conflict with Iran, a commander of the country’s Islamic Revolutionary Guards Corps declared that Iran would soon take “harsher revenge” on the United States for a drone strike last week that killed a top Iranian general.

The slain commander, Maj. Gen. Qassim Suleimani, had led the Quds Force, a powerful branch of the corps, and his death reverberated across the country, prompting calls for revenge and retaliatory strikes by Iran against two military bases in Iraq.

The barrage of missiles on Wednesday took no American lives, Mr. Trump said, and appeared to have inflicted little damage on air bases in Al-Asad and Erbil that house thousands of Iraqi and American servicemen and women. And though Tehran said afterward that it had “concluded proportionate measures” to avenge the killing of General Suleimani, officials in the region cautioned that Iran might not be done maneuvering and had not abandoned its goal to drive the United States out of the Middle East.

A senior commander in the Revolutionary Guards, Abdollah Araghi, said on Thursday that Iran’s armed forces would “impose harsher revenge on the enemy in the near future,” according to a translated report from Iran’s Tasnim News Agency.