When meeting with UN Secretary-General Ban Ki-moon on the sidelines of the UN Conference on Sustainable Development (Rio+20 summit), Wen said the meeting should send a positive and clear signal on the promotion of international cooperation on sustainable development.
The principle of "common but differentiated responsibilities" should be upheld, and the right of every country to choose it own development path be respected, said the Chinese leader.
The Rio+20 summit should also give priority to implementing the Millennium Development Goals on poverty reduction, and to harmonizing the relationships between economic development, social progress and environmental protection, he said.
On Syria, Wen urged the international community to back the mediation efforts by joint UN and Arab League special envoy Kofi Annan and the UN Supervision Mission in Syria.
He also called on all Syrian parties to respect relevant UN resolutions and Annan's six-point peace plan in order to end violence and avoid civilian casualties.
The Syrian government should respond to the popular appeals for reforms, thus creating conditions for a political and peaceful solution to the 16-month crisis, he said.
Ban said China has made remarkable contributions to global economic recovery, South-South cooperation and sustainable development.
Appreciating China's efforts to seek a political settlement of the Syrian crisis, especially its support to Annan's peace mission, the UN chief hoped the international community could send a clear message to all Syrian parties of the need to cease violence and seek a political solution.