"The United States is deeply disappointed that President Paul Kagame has announced his intention to run for a third term in office," John Kirby, a spokesman for the US State Department, said in a statement on Saturday.
Paul Kagame became the country’s vice president in 1994 - the year that marked the end of an infamous genocide in which an estimated 800,000 people were killed. He has been Rwanda’s president since 2000.
The constitutional change allows Kagame to run for a third seven-year term in 2017 elections and enables him to also run for a further two five-year terms.
"With this decision, President Kagame ignores a historic opportunity to reinforce and solidify the democratic institutions the Rwandan people have for more than 20 years labored so hard to establish," State Department spokesman John Kirby said in a statement.
The United States is a major donor and provides military aid to Rwanda, which has close ties with the Western countries including the US and UK/
Paul Kagame has been praised for transforming the country and leading strong economic development since the end of the genocide in 1994.
Under the new constitution Kagame could potentially stay in power as Rwanda’s president until 2034.
"He has violated democratic principles," the spokesman for Rwanda's only opposition Green Party, Jean Deogratias Tuyishime, told Reuters. "This is a failure for Rwanda as a nation."