Cameron is on a three-day Middle East visit, during which he hopes to sell up to 100 Typhoon Jets to the three countries, The Daily Telegraph reported.
"We do believe countries have a right to defend themselves. And we do believe Britain has important defense industries that employ over 300,000 people and so that sort of business is completely legitimate and right," he said of the potential defense contracts during a Monday news conference in Dubai.
Cameron described Saudi Arabia, which has been accused of abuses and repressing its citizens, as "a very old ally and partner."
The contracts, if secured, would be a boost for British defense manufacturer BAE Systems, which had its merger talks with European EADS blocked by the German government last month, the newspaper reported.
Cameron said he is a supporter of the Arab Spring, a series of uprisings that began in 2010, The Independent reported.
"The idea of moving towards more open societies and more open democracies is good for the Middle East and North Africa," he said.