Guterres said in a message sent to the Siem Reap-Angkor Summit on a Mine-Free World being in Cambodia's Siem Reap province, Xinhua news agency reported.
He said the convention represented a solemn commitment to end the legacy of destruction from landmines and that for 25 years, it has driven important progress, with over 55 million anti-personnel devices destroyed across 13,000 square kilometres in over 60 countries.
Also, thousands of people have received lifesaving awareness education and victim assistance services, he added.
"But the threat remains. This includes the renewed use of anti-personnel mines by some of the Parties to the Convention, as well as some Parties falling behind in their commitments to destroy these weapons," Guterres said.
"I call on States Parties to meet their obligations and ensure compliance to the Convention, while addressing humanitarian and developmental impacts through financial and technical support," he added.
Guterres' message was read by UN Under-Secretary-General Armida Salsiah Alisjahbana during the opening ceremony of the summit, which brought together delegates from more than 150 countries, which are state parties to the Mine-Ban Convention.