Venezuela has already begun the process of leaving the regional bloc but the US has renewed calls for its suspension. The US condemned the May elections and called for constitutional order to be resumed.
"No government has the moral authority to recognize or not our government," he said. He added that the threat of suspension was moot because Venezuela began a two-year process in April 2017 to leave the bloc.
"How are they going to eject us from a place we already left?" Arreaza said.
OAS Secretary General Luis Almagro, who has repeatedly criticized Maduro's government, also joined the US in condemning Venezuela, saying the "we must have a continent free of dictatorships."
Bolivia was the only OAS member country to voice support for Maduro during the meeting.
Pompeo's call to suspend Venezuela follows US Vice President Mike Pence's similar call during a speech to the OAS in May. Pence is expected to reiterate the plea during a White House reception on Monday evening for senior OAS officials.
The OAS General Assembly is expected to vote on the US-backed resolution, but it remains unclear if the US motion criticizing Maduro's government would gather the required backing of two-thirds of member states.
Venezuela, which has some of the largest oil reserves in the world, has nonetheless been in the midst of a severe political and economic crisis at home and growing isolation abroad since Maduro first took office in 2013.