WASHINGTON - The White House on Monday confirmed its computer system was targeted in an attack, but the effort was thwarted and no classified networks were compromised.

Spokesman Jay Carney told reporters that it was a "spearphishing attack against an unclassified network."

He said these types of attacks are not infrequent and the White House has mitigation measures in place, according to a White House pool report.

Carney made the remarks to reporters in Henderson, Nevada, where President Barack Obama is preparing for the first presidential debate with Republican challenger Mitt Romney on Wednesday.

"In this instance the attack was identified, the system was isolated and there is no indication whatsoever that any exfiltration of data took place. Moreover there was never any impact or attempted breach of any classified system," said Carney.

Reports of the White House network was attacked last month surfaced earlier in the day. It wasn't clear who was behind the attack.