Speaking during a meeting with New Zealand's Prime Minister John Key, Obama called the attacks "a reminder that the entire international community has a stake in preventing this kind of terror from occurring."
"We have to work cooperatively together on intelligence and in terms of prevention of these kinds of horrible attacks," Obama said.
Obama, who visited Oslo in 2009 to receive the Nobel Peace Prize, fondly recalled his welcome in the NATO ally and said he "wanted to personally extend my condolences to the people of Norway."
"Our hearts go out to them and we will provide any support we can to them," said Obama, who earlier received a briefing on the attacks from his top anti-terrorism adviser John Brennan.
A blast tore through government buildings and a gunman opened fire at a youth meeting of the ruling party, killing at least 11 people.
State Department spokeswoman Heide Bronke Fulton called the attacks "despicable" and said the embassy in Oslo has urged all US citizens to avoid the center of the Norwegian capital.
"The US has reached out to the Norwegian authorities to offer assistance, but there have been no specific requests from the Norwegians thus far," Fulton told AFP.