Ali Abdullah Saleh described a Gulf-brokered deal he was expected to sign later on Saturday as a "coup" dictated by foreign agendas, dpa reported.
"We welcome the Gulf initiative and we will work with it in a positive way for the sake of our homeland," he said. "Though, in reality, it is a mere coup operation."
Saleh made the comments two days after US President Barack Obama asked him to stand aside and only hours before he was due to sign a deal brokered by Abdullatif al-Zayani, the head of the Gulf Cooperation Council (GCC).
The opposition coalition Joint Meeting Parties (JMP) had earlier said they had "received assertion from sources close to the ruling party, as well as external bodies, that the deal will be signed to end the political stalemate in the country."
However, senior JMP member Mohamed Qahtan said he doubted Saleh would sign the deal "after his statements today."
Under the proposed deal, Saleh would be guaranteed immunity from prosecution and would remain head of the ruling party. Power would be transferred to the vice president within 30 days, with presidential elections to take place after 60 days.
Saleh has already backtracked on promises to sign the deal.
Tens of thousands of protesters have been protesting across Yemen, demanding an end to Saleh's 32-year-old rule. At least 140 people have been killed during the unrest.
In his comments Saturday, Saleh also warned against al-Qaeda's presence in the country, predicting that Yemen would be divided again if he were to leave office.