Scotland Yard Commissioner Sir Bernard Hogan-Howe has apologised to Tory former chief whip Andrew Mitchell if his confidence in the Plebgate police probe had been damaged.
Britain's most senior police officer was questioned by the Home Affairs Select Committee over speculation about briefings he held with journalists in March.
Mr Mitchell resigned after he was accused of launching a foul-mouthed rant at officers guarding Downing Street, including calling them "plebs", which he denied.
Tory MP Mark Reckless asked the commissioner if he regretted holding the briefings, and added: "In particular, would you apologise to Andrew Mitchell?"
Sir Bernard replied: "If it's damaged Mr Mitchell's, or anybody else's, confidence in the integrity of our inquiry, then of course I'm sorry."
He said he told reporters he had concerns about the potential damage to the Met's reputation, and that he could not account for news reports published days after the briefings.
A few days after the meetings stories appeared in the Guardian and the Times suggesting there was no evidence that police lied about the affair.
Sir Bernard said he was concerned over whether it would be possible to establish who said what, over calls by the Police Federation for a minister to resign and over allegations that officers could have released information that was incorrect.
In an exchange about the force's policy on meetings with journalists,Sir Bernard said: "More importantly, whichever way this went, it was not going to be good for the reputation of the Metropolitan Police, (that) was my concern."
Eight arrests have been made as part of the investigation, known as Operation Alice, which has cost close to £200,000 so far.
The plebgate row ignited when Mr Mitchell was accused of the heated outburst against officers as he left Downing Street on his bike 19 September.
Pressure intensified after the Daily Telegraph published a police log of the incident, which claimed he called officers ''plebs'' and swore at them repeatedly.
He insisted he did not use the words attributed to him, and later said he was the victim of a deliberate attempt to ''toxify'' the Tories and ruin his career.
An email from a civilian witness backing up the police account of events has also since been called into question.
Some 30 detectives have taken statements from all 800 officers in the Diplomatic Protection Group (DPG) as part of the inquiry, which has taken nine months to date.