Excerpts of the statement were released by the office of Monzer Azbik, chief of staff to coalition chief Ahmad al-Jarba. The opposition group's vote to attend the Geneva talks came on the second day of ongoing meetings in Istanbul.
The coalition statement made clear that the decision did not remove its demand that Assad step down in any transitional government.
"Bashar Assad will have no role in the transitional period and the future of Syria," it said.
The coalition is also expected during its ongoing meetings to approve a list of cabinet of ministers presented by interim prime minister, Ahmad Toumeh, who was elected in September.
The statement on the Geneva talks followed a deal Sunday to ease a blockade on a rebel-held town near the Syrian capital, allowing food to reach civilians there for the first time in weeks, activists said.
That deal is the latest to be struck in recent months between Assad's government and disparate rebel groups in the country's more than 2 ½-year-old conflict.
The Western-backed group had called for goodwill measures from the Assad government, including lifting sieges on rebel-held areas. It wasn't clear whether the deal to ease the blockade on Qudsaya, near the capital, Damascus, was such a gesture, as neither rebels nor Syrian officials comment on such deals.
An activist group, the Qudsaya Media Team, confirmed the truce in a statement but gave few details. In an earlier statement this month, the group said local markets had run out of food, and the area's poorest residents were going hungry. It could not be immediately reached for comment.
Rami Abdurrahman of the Britain-based Syrian Observatory for Human Rights said the deal allowed food and flour to enter the town, under blockade since October. The Observatory monitors the conflict in Syria through a network of activists on the ground.
All warring sides in Syria's civil war have blockaded towns to squeeze the opposing fighters and their support networks, but the most affected have been poor people struggling to buy food, the elderly, the sick and children.
In recent weeks, a variety of Syrian mediators have been trying to ease blockades in several areas, with modest success.
Syria's government is under pressure from the international community to allow food and medical aid into blockaded areas, particularly after reports emerged of widespread hunger in the Damascus suburb of Moadamiyeh this year. It appears civilians have also pressured rebels to accept truces.
Meanwhile, fighting raged for control of a key base protecting the government-held airport in the northern city of Aleppo.
The Brigade 80 base first fell to rebels in February, but the government retook it last week. Activists said it was recaptured by rebels overnight Friday, but by Sunday afternoon, troops loyal to Assad were again in control, said the Observatory and a Lebanese television channel that closely follows Syria.
The rebels fighting at Brigade 80 have been led by fighters from the Islamic Tawhid Brigade and two al-Qaida-linked groups, the Nusra Front and the Islamic State in Iraq and the Levant.