The eruption began on Sunday afternoon and authorities said around 100 properties had so far been destroyed by lava.
No deaths have been reported.
The four evacuated villages included El Paso and Los Llanos de Aridane, with temporary shelters set up to house the displaced residents.
Lava was still flowing at 700 m (2,300 feet) per hour on Monday, according to the Canary Islands Institute of Volcanology, but mostly through uninhabited areas.
Canary Islands President Angel Victor Torres on Sunday asked residents to “stay in their homes” after people from across the island blocked roads trying to approach the volcano.
“It is not foreseeable that someone else will have to be evacuated,” he said.
Mariano Hernandez, president of the island of La Palma, also asked people to stay away and told Spanish radio Cadena Ser that lava had destroyed around 100 homes so far.
Local airline Binter said it had canceled four flights to and from the neighboring island of La Gomera.
Spain’s Prime Minister Pedro Sanchez arrived in La Palma on Sunday evening to meet with Torres as part of the overseas rescue efforts.
The Prime Minister has delayed his departure to attend the United Nations General Assembly in New York.
A magnitude 4.2 earthquake was recorded before the eruption, which took place in Cabeza de Vaca on the western slope of the ridge that descends towards the coast.
La Palma was on high alert after more than 22,000 tremors were reported within a week.
Cumbre Vieja is part of a chain of volcanoes that experienced a last major eruption in 1971 and is one of the most active volcanic regions in the Canaries.
It lies to the south of La Palma, which is home to around 80,000 people.
Itahiza Dominguez, head of seismology at the Spanish Geological Institute, told Canary Islands TV that while it was too early to say how long the eruption would last, previous eruptions had lasted for weeks or even month.