The Prime Minister pledged to retain the "triple-lock" guarantee of minimum annual pension rises of 2.5% until 2020 if the Tories won the next election.
He said it was right to prioritise "security" for people in their old age while austerity continued to bite.
But he failed to carry over a pledge to continue winter fuel payments, free prescriptions, bus passes and TV licences for all pensioners.
"I made a very clear promise. We've kept that promise," he said amid mounting pressure to remove such perks from better-off OAPs. "We will set out our plans at the next election in our manifesto."
Labour plans to strip winter fuel payments from the richest 5% of pensioners and the Liberal Democrats have also said they would means-test the benefits.
Under the "triple lock" the basic state pension rises in line with inflation, wages or 2.5%, whichever is highest.Mr Cameron said the protection had been made possible by "difficult decisions" such as extending the retirement age, meaning millions in their 30s and 40s will wait longer to get a pension. "Politics is about choices and the choice I make is: yes, we should be giving pensioners dignity and security in their old age," he said in an interview.