The White House on Friday called for restraint in Yemen, amid reports that the country's president was wounded in a rocket attack.

National security council spokesman Tommy Vietor said the U.S. was monitoring reports that President Ali Abdullah Saleh was wounded Friday, but could not confirm them. He said the U.S. is very concerned about the escalating violence in Yemen and said the dispute there will only be solved through negotiations.

A Yemeni government official said Saleh was slightly injured when rockets struck his palace Friday. It's the first time opposition tribesman have targeted Saleh's palace directly.

The Pentagon said there was no move now to bring U.S. troops in Yemen out of the country.

"We do still have some service members in the country and they take necessary precautions. Beyond that, I won't talk specifics," Defense Department spokesman Col. Dave Lapan said, declining to give the number of U.S. troops there helping train local counterterrorism forces.

Lapan said there is no evidence that Yemeni forces trained by the U.S. are being used against peaceful protesters.

"We have seen reports that they have been engaged with armed forces, and are looking for more information on that aspect," Lapan told Pentagon reporters. "We still have not seen any evidence that those forces we helped train were used or have been used against unarmed protesters."

Top Obama counterterrorism aide John Brennan will be discussing options for addressing the deteriorating situation in Yemen during meetings with government officials in the Middle East this week, Vietor said.