The United States in the "strongest terms" condemned the violence in Yemen on Friday that included an attack on the presidential palace in Sana'a that injured long time leader Ali Abdullah Saleh, dpa reported.
"The United States condemns in the strongest terms the senseless acts of violence today in Yemen," White House spokesman Jay Carney said.
Months of violence between protesters seeking to oust Saleh and government forces have gradually worsened and brought the country closer to civil war. Salah, who has ruled the country since 1978, had initially pledged to step down, but has since relented.
Saleh has refused to sign an agreement brokered by neighbouring countries known as the Gulf Cooperation Council (GCC) that would have Saleh transfer power in return for immunity from prosecution.
The US has called on Saleh, who has stood with Washington in the war on terrorism, to adhere to the GCC proposal by leaving office.
"We call on all sides to cease hostilities immediately and to pursue an orderly and peaceful process of transferring political power as called for in the GCC-brokered agreement," Carney said.
Saleh was being treated for minor injuries he received when his palace was hit by shelling.