The chief negotiator for the opposition Movement for Democratic Change (MDC), Tendai Biti, had told reporters on Tuesday that Tsvangirai would not travel to the summit unless he received his passport.
But Tsvangirai dropped the demand, saying that he would attend the summit even if the government refused to grant him a passport.
"With or without a passport, I will attend," he said in Bulawayo, Zimbabwe’s second city, where he attended the launch of a video about 1980s human rights abuses.
Tsvangirai has not had a passport for months, and must seek an emergency travel document valid for a single trip each time he leaves the country.
Biti had called the government’s failure to grant him a normal passport "the crudest form of lack of sincerity" by President Robert Mugabe.
Leaders from the 15-nation Southern African Development Community (SADC) are expected to hold an emergency summit aimed at pressing Tsvangirai and Mugabe to resolve their differences on forming a unity government.
The rivals agreed to a power-sharing deal on September 15, but talks have stalled over how to divide control of powerful cabinet posts.
Regional leaders met twice last month in a bid to press them into a deal, but they remain deadlocked over control of the home affairs ministry, which oversees the police.
The date and location of the summit have not yet been announced.