About 8000 protesters led by the opposition Solidarity Movement on Wednesday occupied the People Power Monument on a Manila highway, the site of the 1986 popular uprising that toppled dictator Ferdinand Marcos.
Elsewhere, police blocked about 2000 marchers headed towards the Malacanang presidential palace.
The administration-dominated House of Representatives on Tuesday voted 158-51 to toss out three impeachment complaints against Arroyo.
"Since they have closed off the process in Congress, we are opening up the streets as an option for the people," said Representative Teddy Casino of the left-wing Bayan Muna party.
As the House concluded a 23-hour marathon session on Tuesday, former president Corazon Aquino and Susan Roces, the widow of Arroyo's chief rival in last year's election -Fernando Poe Jr.- led 10,000 protesters in a march on the legislative building.
It was stopped by hundreds of police. Addressing those at the monument, Roces said: "I have no message for you. You are the ones who have the right to say what you want to do."
She pointed the microphone toward the crowd, which chanted: "People power! People power!"
"We cannot achieve unity with Mrs. Arroyo at the helm, for Mrs. Arroyo is the problem"
"I will support you," she said in response. In a statement on Tuesday, Arroyo said she was grateful that Filipinos adhered to the constitutional process "instead of forcing a president out of office through 'people power'."
On Wednesday, she repeated her call for reconciliation, but the opposition said she was insincere.
"We sincerely believe in the need for national unity in the face of our many problems, but we cannot achieve this unity with Mrs. Arroyo at the helm, for Mrs. Arroyo is the problem," said a statement from the Solidarity Movement.
"We urge our people to actively express their protest and defiance against this illegitimate and immoral regime," it said.
Anti-Arroyo protests have attracted only a fraction of the crowds that ousted Marcos in 1986 and former president Joseph Estrada in 2001.
Although the impeachment case has been thrown out, some charges leveled against Arroyo - including rigging last year's election, bribery and corruption - will be investigated by the 23-member Senate, which traditionally asserts its independence from the president.
The investigation could lead to new laws dealing with similar cases in the future.
Senator Rodolfo Biazon, who leads the Senate committee on national defence and security, said he will call for testimony from officers mentioned in wiretapped conversations allegedly related to election fraud.
Arroyo has many allies who dominate
Biazon did not set a date for the hearing but expects it to start after a two-week congressional recess this month.
Vote-rigging accusations against Arroyo emerged in June, based on wiretap recordings in which she purportedly discussed ensuring a million-vote victory with an elections commissioner.
Arroyo apologised for a "lapse in judgment" for talking with the official before results were announced but said she did not influence the count.
Another Senate committee is set to investigate a police and military intelligence raid on the house of a retired handwriting expert who examined allegedly doctored election results that were to be presented as opposition evidence of poll fraud.