The attack comes after Cameron told the House of Commons Liaison Committee that he does not think that the accession of Turkey to the European Union is "remotely on the cards."
Speaking on Tuesday, the Prime Minister said, "I don't think it will happen for decades. The facts are it requires unanimity of all the member states.
"So I'd say very clearly to people, if your vote in this referendum is being influenced by considerations about Turkish membership of the EU, don't think about it. It's not remotely on the cards."
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Eurosceptics, though, say his comments this week represents a massive change of stance compared with earlier statements when Cameron said he was the "strongest possible advocate for EU membership" for Turkey.
The attack on Cameron comes amid a growing power struggle between Turkey's Prime Minister Ahmet Davutoglu and President Recep Tayyip Erdogan.
This reached a head on Thursday with Erdoğan forcing Davutoğlu's resignation. The ruling AK Party will now hold an extraordinary convention 22 May to elect its new leader and the country's chief executive office holder.
As the outgoing prime minister, Davutoğlu confirmed that he would not stand for nomination.
The change in the power constellation in Turkey came just a day after the European Commission conditionally recommended to proceed with visa freedom with Turkey.
Having commended Ankara's recent efforts to comply with the 72 technical criteria set out as conditions for the lifting of visas, the Commission nonetheless stated that Turkey would still need to fulfil five of them to achieve this objective.
With Turkey's latest power shift threatening to challenge its relations with the EU, UKIP has questioned Cameron on his new comments about Turkey.
The party points out that in 2010 at Ankara, he told his Turkish counterparts: "I will remain your strongest possible advocate for EU membership… this is something I feel very strongly and very passionately about. Together I want to pave the road from Ankara to Brussels."
At the time, he said, "I am here to make the case for Turkey's membership of the European Union and to fight for it."
UKIP says the Prime Minister said in 2013 : "Britain has always supported the widening of the EU. Our vision of the EU is that it should be a large trading and co-operating organisation that effectively stretches, as it were, from the Atlantic to the Urals."
UKIP deputy leader Paul Nuttall said, "It is British government policy of long standing to support Turkish accession. Why is Cameron talking about having a veto when it is his government's policy to support accession?
"The EU has in the process of giving Schengen visa-free travel to the peoples of Turkey, Ukraine, Kosovo, and Georgia. This is a population of 127 million people with a right to come to the Schengen area, right up to the English Channel. Given that weakness of the border at Calais - it is clear that David
Cameron cannot promise to make our borders watertight to people eager to come to the UK."
The MEP said, "It is clear that David Cameron is trying to mislead the British people about the reality of Turkish accession talks and the EU's visa-free regime. His conduct in this matter is disgraceful."