"When it comes to telephone calls, nobody is listening to your telephone calls. That's not what this programme's about," Obama said in response to a question at a public meeting in California where he is travelling.
Defending his administration's decisions in this regard, including seeking information about internet and email usage of foreigners, Obama asserted that this has helped the US prevent terrorist attacks.
"What the intelligence community is doing is looking at phone numbers and durations of calls. They are not looking at people's names, and they're not looking at content," Obama said.
"But by sifting through this so-called metadata, they may identify potential leads with respect to folks who might engage in terrorism," he said.
"If the intelligence community then actually wants to listen to a phone call, they've got to go back to a federal judge, just like they would in a criminal investigation. So I want to be very clear. Some of the hype that we've been hearing over the last day or so -- nobody's listening to the content of people's phone calls," the US President clarified.
His assurances came amid reports appearing in several media outlets - The Washington Post and Guardian - that the US intelligence agencies have been secretly taking information on foreigners overseas for years from companies like Google, Facebook and Apple in search of security threats.
"We strongly object to using that power in this manner," The New York Times said in an editorial.
"The administration has now lost all credibility. Mr.
Obama is proving the truism that the executive will use any power it is given and very likely abuse it," the daily said.
In a report, The Washington Post said under the programme codenamed PRISM, the National Security Agency and the FBI are tapping directly into the central servers of nine leading US Internet companies - Microsoft, Yahoo, Google, Facebook, PalTalk, AOL, Skype, YouTube, Apple - extracting audio and video chats, photographs, e-mails, documents, and connection logs that enable analysts to track foreign targets.