Ross Garber, Rowland's chief legal counsel, said the subpoena (search) "tramples on the mandate of the balance of separation of powers."
The state House Select Committee of Inquiry had ordered Rowland to appear June 8.
Garber said there are conditions under which the governor would testify. But he refused to elaborate on what those conditions are, other than to say that the committee "would certainly have to withdraw its subpoena."
Rowland, a three-term Republican, is under federal investigation for accepting gifts from state contractors, friends and subordinates. He has maintained he provided nothing in return to the gift-givers.
The governor has often said he wants a chance to tell his side of the story to the 10 legislators on the panel, which is deciding whether to recommend his impeachment.