Trump has openly criticized Sessions in a series of Twitter statements in the recent days after the chief prosecutor recused himself from a Justice Department probe into alleged Russian meddling in the 2016 US election.
Trump also bashed him for not firing several top Justice Department officials and not pursuing a criminal investigation of defeated presidential candidate Hillary Clinton.
On Thursday, US upper house lawmakers took measures to prevent Trump from sacking Sessions during Senate's August recess. The Senate will convene for pro forma sessions every three days until September, which will not allow the president to make new unilateral appointments.
On Friday, Sessions said that the fight against disclosing classified information would be enhanced. According to the official, four people have already been charged with unlawfully disclosing classified material or with concealing contacts with federal officers.
The American Civil Liberties Union (ACLU) said in a press release on Friday that Sessions' announcement can be viewed as a crackdown on freedom of the press and democracy.