The Prime Minister spoke to German Chancellor Angela Merkel and European Council President Herman Van Rompuy ahead of a European Council summit.
Ukraine will be a key issue at the talks, which will also consider new appointments to the roles of council president and high representative. The latter post is currently held by Britain's Baroness Ashton.
On the Ukraine crisis, a Downing Street spokeswoman said: "[Mr Cameron and Mrs Merkel] agreed that Saturday's European Council should address the ongoing situation in eastern Ukraine, including Russia's provocative actions. Both leaders agreed that there could be no military solution to the crisis and President Putin had to enter into negotiations in good faith to find a political solution."
Ukraine has accused Russia of launching a new military incursion across its eastern border, dampening hopes that Tuesday's talks between their two presidents could have marked a turning point in a five- month-old crisis.
Ukrainian military spokesman Andriy Lysenko said a group of Russian soldiers had crossed the border in armoured infantry carriers and a truck and entered the town of Amvrosiyivka, not far from where Ukraine detained 10 Russian soldiers on Monday.
The Downing Street spokeswoman confirmed David Cameron had also spoken to President Van Rompuy about the summit, "including the appointment of the new council president and high representative and the situation in Ukraine, on which they agreed that the EU should continue to put pressure on President Putin to de-escalate the situation".
"They also agreed leaders should address the situation in Iraq and Syria and how the EU can help to co-ordinate national responses, including efforts to tackle foreign fighters," he said.