President Reagan's instructions to special U.S. envoy Philip C. Habib were a matter of dispute in Washington and Manila yesterday, with the administration doing little to clear them up.

In the Philippine capital, Habib denied a Washington Post report that he had warned Marcos to "make democratic reforms and share power with opposition forces" or risk losing U.S. aid.

At his morning briefing yesterday, White House spokesman Larry Speakes was asked whether "Habib told Marcos that unless there was reform in the government there that he faced a cutoff of U.S. aid." Speakes replied:

"Habib is out there to assess the situation, to make a report to the president and to make recommendations . . . . I do not know his specific conversations with President Marcos. I do know that our position has been that reform in the economic, political and military sectors are essential for Philippine progress in the democratic process."

A senior State Department official in Washington disputed The Post report, saying that "Habib did not threaten aid cutoffs or call for reforms as a way to deal with the current postelection problem" in his discussion with Marcos. The official, who asked not to be quoted by name, said that "Habib doesn't have instructions to tell Marcos to do something" and that he is not recommending a power-sharing arrangement to Marcos or the opposition headed by Corazon Aquino under present circumstances.

Habib was described as seeking a possible "basis for a solution" without bringing a preferred solution.

A White House official, who also asked not to be quoted by name, said The Post report was accurate. He emphasized that Reagan had made no decision on what to do about the "fraudulent" election and said Habib had broad authority to explore ways to resolve the crisis.

The official went on to say that Habib "could hardly confirm that he had talked tough to Marcos -- that would have been a public beating up of him on Philippine soil" and thus endanger his diplomatic mission.