Russian computer hackers targeted the databases of the Republican National Committee (RNC) but failed to penetrate its security defenses, the Wall Street Journal reported on Friday, citing U.S. officials with knowledge of the attempted intrusion.

Russian hackers attacked the RNC but their attempt to access the Republican network was "less aggressive" and "much less persistent" than the attack on the Democratic National Committee, the newspaper said. Only one email account of a former Republican official was targeted, it added.

The report comes after a fraught election campaign where senior U.S. national security officials concluded that Russian intelligence agencies hacked the Democratic National Committee. U.S. intelligent services said they stole emails from Democratic officials, including the chairman of Hillary Clinton's presidential campaign. Russian officials have strongly denied the accusations.

"A senior U.S. official said analysts now believe what started as an information-gathering campaign aimed at both parties later took on a focus of leaked emails about Mrs. Clinton and Democrats," the newspaper said.

The RNC was not immediately available for comment when contacted by CNBC.

Read the full article by the Wall Street Journal here.