The president, on the second day of his official visit to Beijing, told students at Peking University: "Perhaps such strategic cooperation between our countries does not please everyone, but we understand that interaction is in the interests of our nations, and we will strengthen it in all possible ways - whether people like it or not."
Russia and China have taken a shared stance on many global issues in recent years, often opposing the position of the United States.
On Friday, the Russian leader signed a joint declaration with his Chinese counterpart Hu Jintao, condemning U.S. moves to establish a global missile defense system, and saying the plans threaten the global strategic balance.
The plans also weaken "confidence-building measures between countries and the consolidation of regional stability," yesterday's statement said.
Medvedev told the group of students: "Russian-Chinese cooperation is now becoming a key factor in international security - a factor without which it would be impossible to take fundamental decisions through international cooperation."
He also said new spheres of cooperation should be developed through the Shanghai Cooperation Organization (SCO), particularly the sphere of energy.
The SCO, a regional bloc comprising Russia, China, Kazakhstan, Tajikistan, Kyrgyzstan, and Uzbekistan, primarily addresses security issues, but has recently moved to embrace various economic and social projects. The SCO has been widely seen as a counterweight to NATO in the region.
"Within the framework of this organization we are able to coordinate new directions of cooperation, including on the energy issue," Medvedev said.
Earlier in the day, the president visited a monument on Tiananmen Square, and later met with the chairman of the National People's Congress.
He laid a wreath at the Monument to the People's Heroes, built in the 1950s to commemorate those who died defending China in the 19th and 20th centuries.
During his meeting with National People's Congress Chairman Wu Bangguo, Medvedev stressed the importance of parliamentary ties between the two countries.
"These are vital contacts. It is good that our contacts are being developed not only on the level of the top leadership... We hope that parliamentary cooperation will continue in the future," Medvedev said.
The president also expressed his condolences to the Chinese people over the May 12 earthquake in the Sichuan province, which has claimed between 60,000 and 80,000 lives.
Wu told Medvedev his country highly values Russia's support in the quake-hit area.
Russia "sent humanitarian aid, and swiftly came to us with a team of Russian rescuers. Real friendship is shown in difficult times, as we say in China. This is a genuine reflection of the nature of our relations," the chairman said.
Russia will send nine military planes to China later today carrying equipment for the ongoing relief operation, in line with instructions issued by Medvedev to Defense Minister Anatoly Serdyukov.
Gen. Vladimir Isakov, a deputy defense minister, said: "Nine planes will urgently be sent to deliver 23 mobile kitchens, 300 large army tents, and 3,000 woolen blankets."
A Russian Mi-26 helicopter left for China today carrying two rescue teams to help with the relief operation.
Chinese Premier Wen Jiabao said earlier that the death toll in the Sichuan province could rise to 80,000 as most of the missing are presumed dead.
The disaster has left over five million people homeless.