"We don't really have an exit strategy. We have a victory strategy. We are here for a mission to set the country on the path of democracy, freedom and representative government," Rumsfeld said on Tuesday.
"We have to see the institutional capacity developed so that they can take over the security responsibility and as that takes place the responsibility of the coalition forces will decline and they will be able to move away and leave this country with the full responsibility for its own country."
Iraq's new leaders have said the local security forces, which are being trained by the US military, are weak and not yet ready to take over full responsibility for security in a country still battling fighters opposed to the presence of foreign troops.
But there have been a number of street demonstrations in recent days with Iraqis calling for the 140,000 US soldiers to leave immediately.
Asked if the US planned to have permanent bases in Iraq, Rumsfeld said the issue would have to be discussed with the government that emerges after a permanent constitution is in place and new elections are held in December.
"We do not currently have any plans for any permanent presence in this country," he said, adding: "It wouldn't be proper for us to discuss [this issue] with the transition government."
Rumsfeld urged new interim President Jalal Talabani and interim Prime Minister Ibrahim al-Jafari to stick to a timetable set in transition laws passed under the previous US-led occupation authority which call for the constitution to be put to a referendum in October.
"I sure hope no delay occurs. Some may say we cannot do this, let's delay it," he said. "I think the Iraqi people deserve to have a constitution."