The offence under section 7 of Prevention of Corruption Act, 1988 was registered against Police Sub Inspector Vikram Naik attached to Ponda Police Station after he was found demanding the bribe.
Nelson Antao, a local resident had complained to the ACB about conduct of the PSI, a senior ACB official said.
The accused PSI was investigating a case against one Agnelo Fernandes who is wanted by police for allegedly assaulting his own wife.
The police had suspected that Antao had sheltered Fernandes, who has been on the run.
The accused had threatened to arrest Antao, if money is not paid.
The ACB has written to Director General of Police (DGP) about the case against the PSI while investigations under Prevention of Corruption Act is also on, he said.