Earlier this month Noel Anjo, an outspoken critic of the government, claimed he was bashed at the prime minister's home in 2009.
A front page newspaper story, supported by PNG's opposition, reported Mr Anjo's allegations that plain clothed police took him to Sir Michael's official residence, where the prime minister and his wife Lady Veronica Somare repeatedly punched him.
In parliament on Wednesday, Sir Michael rejected Mr Anjo's claims.
"I can assure this parliament that Veronica and I never laid a finger on Noel Anjo let alone order any kidnapping," Sir Michael said.
"These claims remain allegations until they are proven.
"I want to let this house know that to date no charges have been laid against me.
"Only if the matter is taken up in court will I be obligated to answer to these politically-motivated claims.
"Nobody should put up with the kind of venom that my entire family has been subjected to over the recent number of years that I have been in office," he said.
The opposition's campaign against the government has repeatedly focused on numerous scandals that have plagued the two-term Somare government.
Thwarted attempts to topple the government this year with a vote of no confidence saw a mass defection to the opposition, including the former deputy prime minister Puka Tumu.
But despite the occasional wobble, the Somare government remains in tact and presides over strong economic growth.
However, opposition deputy leader Bart Philemon on Tuesday said the Somare government had not translated that economic growth into other areas.
"Despite eight years of political stability and unprecedented levels of revenue, the Somare government has failed to address strategic areas such as good governance and rising corruption, the public service has become bloated, ineffective and highly unproductive," he said.