Speaking in Brussels on Monday, the Norwegian official said, "The ceasefire is being violated every day, sometimes hundreds of times, with explosions from equipment banned under the Minsk agreements.
"That is because heavy weaponry has not been withdrawn and only 13 per cent of the equipment registered with the OSCE can currently be traced. As Ukraine continues to face Russia's aggressive actions, Nato stands by Ukraine with strong political and practical support."
Stoltenberg was speaking at a news conference ahead of Nato's foreign affairs ministerial meeting on Tuesday and Wednesday at its Brussels headquarters.
Over the next two days, the foreign ministers will meet and address pressing security challenges and how the alliance is responding to them.
On Wednesday, the organisation will also hold a meeting of the Nato-Ukraine commission.
Stoltenberg said, "First, they will discuss Nato/EU cooperation because stronger cooperation between Nato and EU is one key way to strengthen our response to a more challenging security environment.
"At a time when the peaceful order is being challenged in new ways, Nato and the EU need to work closer than ever before. Over the last couple of years, we have been able to create new momentum in our partnership and reach a new understanding of the importance of our cooperation."
He added, "At all levels, from staff-to-staff talks, to my regular meetings with Presidents Tusk and Juncker and foreign affairs chief Federica Mogherini we have moved step by step, in a pragmatic way which benefits all our nations, and this week, I expect we will take a significant step forward: by endorsing a package of more than 40 measures to implement the joint declaration which I signed together with Tusk and Juncker in July in Warsaw.
"This aims to deepen our cooperation in seven areas, including countering hybrid and cyber threats, working together in maritime operations, and on capability development. Cooperation with the European Union is also an important way in which Nato projects stability beyond our borders.
"On Tuesday, we will discuss the progress we've made in boosting the capacity of our neighbours to the east and to the south, including our support to the counter-Isis coalition, our training of Iraqi officers and our new operation sea guardian in the Mediterranean.
"Nato has many years of experience in projecting stability in the western Balkans and in Afghanistan."
Stoltenberg went on, "On Wednesday, we will meet with the Afghan foreign Minister to reaffirm our commitment to supporting Afghans to secure their own country and to review Afghanistan's reforms, which are linked to continued international support.
"Nato's presence in Afghanistan demonstrates our long-term commitment to the fight against terrorism. It is helping to stabilise the region and stem the flow of migrants and refugees."
He said this week's meeting of foreign ministers is an "important building block" for a Nato summit next year in Brussels.
Stoltenberg said, "I look forward to welcoming the new US President Donald Trump to the summit, and to working with him and his national security team as Nato continues to adapt to the challenges we face."