Ryan said Comey had also lost Trump's confidence, adding that the president had acted within his authority while removing him.
Echoing the White House, the Republican said appointing a special prosecutor to investigate Russian ties to Trump's presidential campaign would be a bad idea.
"We have three investigations going on right now. We have a House investigation by our Intelligence Committee. We have the Senate Intelligence Committee doing an investigation, and you have the FBI investigating all things Russia," he said in a TV interview.