The students threw rocks at police, who in turn responded with tear gas.
It's the latest in a string of anti-government protests that have been staged across the country since February 12 leaving at least 15 people dead and 150 injured.
Maduro invited Governor Henrique Capriles, the opposition candidate in the last two presidential elections, to attend the dialogue,
"He could have come here to speak like all of you, without problems, I would have listened to him," said Maduro.
"Right now they (government authorities) are repressing (protesters) in various parts of our country, two people have lost their lives so far today, how can I go and present myself at a session in the palace (presidential palace) in a hall with air conditioning," he said.
Capriles also said he would not participate while another opposition leader, Leopoldo Lopez, remains jailed along with dozens of others who have taken part in anti-government protests.
Lopez, a former mayor of a district in the capital, is being held in a military jail outside Caracas on charges that include criminal incitement of violence for organizing a mass opposition rally on February 12 that set off a wave of unrest across the country.
Though violent protests have died down, Venezuela remains tense.
In the city of Maracaibo, in north-west Venezuela around 500 kilometres (311 miles) west of Caracas, protesters set up barricades across the streets and heckled passing policemen but no violence was reported.
Since February 12, opponents of Maduro have been staging countrywide protests that the government says have left at least 15 people dead and wounded about 150.