"Something like this is always distracting and very disappointing and I hope we can, by doing what we're doing here, put to rest the whole situation," McCain said.
McCain also denied that he had ever improperly aided companies represented by Iseman as chairman of the senate commerce committee.
"At no time have I ever done anything that would betray the public trust," the senator said.
McCain is almost certain to win the Republican nomination for November's presidential election.
He and four other senators were accused two decades ago of trying to influence banking regulators on behalf of Charles Keating, a savings and loan financier later convicted of securities fraud.
The Senate Ethics Committee ultimately decided that McCain had used "poor judgment" but that his actions 'were not improper" and did not deserve punishment.
McCain has said that incident inspired him to attempt to change campaign finance laws in an attempt to reduce the influence of money in politics.
The Arizona senator is course to win the Republican nomination for president, but conservatives have voiced concerns over his record on immigration and tax issues.