His comments came after he agreed to a plan that would see him step down, in return for immunity from prosecution.
Opposition parties welcomed the plan, but protesters are still pressing for Mr Saleh's immediate departure.
There were fresh anti-government demonstrations in the capital, Sanaa, and in other parts of the country on Sunday.
"No negotiation, no dialogue - resign or flee," protesters in the capital chanted.
At least 130 people have died during two months of protests in Yemen inspired by uprisings elsewhere in the Arab world.
'Chaos' Mr Saleh told the BBC continuing protests could escalate the crisis.
AnalysisWhen President Saleh met us in his library he displayed a great deal of confidence about his current situation. He seemed relaxed during the interview but was concerned about Yemen's future.
He claims al-Qaeda has infiltrated the opposition movement and that the West will pay a price if it encourages them.
The president says he will leave office immediately if a majority of Yemenis ask him to do so. But the protesters are a minority, he says, who should follow the majority's wishes, under his understanding of a democratic system.
He also accused the West of double standards over the Yemen protesters. The West, he says, wants him to respond to minorities' requests which is against the principles of democracy.
When you speak to the opposition activists, there's a great deal of scepticism. They dismiss the initiative from the Gulf states to transfer power from President Saleh saying that they don't trust his promises. They are planning to increase their demonstrations until he leaves office, they say.
"Any coup is rejected because we are committed to the constitutional legitimacy and don't accept chaos."
He also claimed that Islamist extremists had infiltrated protest camps.
"Al-Qaeda are moving inside the camps and this is very dangerous," he said. "Why is the West not looking at this destructive work and its dangerous implications for the future?"
The transition plan was drawn up by Gulf Arab states belonging to the Gulf Co-operation Council (GCC).
Under it, Mr Saleh would hand over to his vice-president one month after an agreement is signed with the opposition, and presidential elections would follow a month later.
Mr Saleh, his family and his aides would gain immunity from prosecution.Continued