Speaking on television Thursday, Siniora said dialogue between political parties is needed to end the crisis, The Lebanon Daily Star reported.
Some parties use democracy to disrupt the political process, he said. He charged they are trying to undermine a democratically elected government.
"When it is not convenient anymore, they turn their back against it and reject dialogue," he said.
Siniora and President Emile Lahoud are expected to head rival delegations to the Arab League summit next week in Saudi Arabia.
"Anyone from the ousted Cabinet who would like to accompany me should submit his resignation first because this Cabinet is illegitimate and unconstitutional," Lahoud said Friday.