Addressing Trump, Schiff wrote on Twitter, "Your attack against a whistleblower increases the chance that corruption goes unreported, and heightens risk of an illegal reprisal."
Pelosi said in her statement that the "stonewalling must end immediately, and the whistle-blower must be provided with every protection guaranteed by the law."
Michael Atkinson, the intelligence community's inspector general, told the Intelligence panel at a closed-door briefing on Thursday that the whistle-blower's complaint focused on a specific sequence of events, according to a person in the room. Atkinson wouldn't say whether the events involved Trump.
Three congressional committees are investigating whether Trump withheld military aid to Ukraine in order to pressure the country's new president, Volodymyr Zelenskiy, into reopening an investigation into a company linked to Biden's family. It's unclear whether the whistle-blower complaint is directly related to the Biden allegation.
Schiff and other Democratic House chairmen said that Trump lawyer and supporter Rudy Giuliani pressured Ukraine to investigate Biden and suggested that the administration threatened to withhold US security assistance to the country.
Giuliani said Thursday night on CNN that he urged the Ukrainian government to investigate corruption, "and I'm proud of it." He said he didn't know whether Trump had talked to Ukraine's president about the issue but even if so "it doesn't mean a damn" that a president would inquire about evidence of corruption.
"I don't know if he did, and I wouldn't care if he did," Giuliani said. "He had every right to do it if he was the president of the United States."
Ukraine's prosecutor general said in May that he had no evidence of wrongdoing by Joe Biden or his son, Hunter Biden, who sat on the board of one of the country's biggest gas companies.
A next step in the whistle-blower investigation is set for September 26, when Acting Director of National Intelligence Joseph Maguire is scheduled to testify publicly before the House Intelligence panel after initially resisting demands to do so. Maguire is also expected to meet at some point next week with the Senate Intelligence Committee.
Jason Klitenic, the general counsel of the Office of the Director of National Intelligence, had told Schiff in a letter on Tuesday that the law didn't require that the complaint be turned over to Congress based on guidance by the Justice Department.
The refusal to provide the information has provoked the latest clash between congressional committees that are pursuing investigations of Trump and his administration, and a White House that largely refuses to cooperate.
Trump earlier Friday denied any wrongdoing and accused the whistle-blower of being "highly partisan," without substantiation.
The dispute comes as Trump is weighing how to respond to an attack on Saudi oil facilities that US officials have blamed on Iran. It became public during the same week that Trump selected a new national security adviser, Robert O'Brien, after ousting John Bolton.
