Ms Youssef was inside the Thornlie mosque last month when it was attacked, with four cars being set on fire and anti-Muslim graffiti written.
“The first thing we thought was we hoped no one got injured or anyone got killed,” he said.
“It was a really big worrying couple of minutes and we stayed there and offered our support if they needed.”
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READ NOWMr Youssef is preparing for the Multicultural Eid Carnival on Saturday, July 16.
He said he had stepped up security for the carnival after the attacks.
“We want to spread a peaceful message to anyone and in the Muslim community to see what we do and how we promote through community,” he said.
“Last year a lot of the mainstream community came through carnival and feedback was very positive.”
He said it was a very small minority that ruined it for everyone.
More than 12,000 people attended last year’s carnival.
This year there will again be food, music rides and games for children. The carnival is going to have a special fireworks display to celebrate the end of Ramadan with people from all cultural backgrounds.