Ban also on Thursday appealed for new efforts to convene a peace conference on Syria.
The UN chief and US Secretary of State John Kerry told reporters at the United Nations that there could be no military solution to the 28-month-old conflict.
Ban said: "More than 100,000 people have been killed, millions of people have either been displaced or become refugees in neighboring countries.”
"We have to bring this to an end. The military and violent actions must be stopped by both parties, and it is thus imperative to have a peace conference in Geneva as soon as possible."
The United States and Russia vowed in May to press for a follow-up to a peace conference held in Geneva last year, which set out a transition plan.
However, divisions in the international community and disagreements between the Syrian government and opposition about the goals of such a conference have blocked efforts.
Ahmad Jarba, the president of the so-called Syrian National Coalition, was in New York on Thursday for talks with Kerry ahead of a Friday meeting with UN Security Council envoys.
Kerry said there are "enormous levels of suffering".
"There is no military solution to Syria, there is only a political solution. That will require leadership in order to bring people to the table," he added.
Kerry said he spoke on Wednesday with Russia's Foreign Minister Sergei Lavrov.
"We remain committed to the effort to bring the parties to a Geneva II, to implement Geneva I, and we will try our hardest to make that happen as soon as is possible," he said.
Ban has previously said he would like a peace conference in September. But UN diplomats say the conflict is now so bitter that they doubt the two sides can be brought to the negotiating table.
US President Barack Obama's plan to provide anti-Syria militants with weapons and strategic military aid is gaining traction in Congress, according to US lawmakers.
Washington is currently providing humanitarian and non-lethal military aid to militant groups.
The US government promised an expansion of military aid to Syria's terrorist forces in June, but such aid has yet to be disbursed.
BA/