He added there could be a potential easing of sanctions if the power sharing deal was met.
"The US will only consider new development assistance and easing of targeted sanctions when we have seen evidence of true power sharing as well as inclusive and effective governance," spokesperson Robert Wood said in a statement.
"We will continue to provide humanitarian assistance to the Zimbabwean people in their time of suffering," Wood said.
Zimbabwe’s main opposition party, the Movement for Democratic Change (MDC), decided on Friday to join a government of national unity with President Robert Mugabe’s Zanu-PF, ending a protracted deadlock more than four months after signing a power sharing deal.
Wood said "the success or failure of such a government will depend on credible and inclusive power sharing by Robert Mugabe and his Zanu-PF party."
He also called on the international community to "remain engaged and continue to scrutinise actions by Mr Mugabe to ensure adherence to the letter and spirit of this agreement, including respect for human rights and the rule of law." – SAPA