Pakistan's Foreign Secretary Aizaz Chaudhry was quoted in the Dawn newspaper as saying he was surprised by the announcement and had asked the Pakistani ambassador in Riyadh for clarification.
The country's foreign office said in a statement later on Wednesday that it was "awaiting further details to decide the extent of its participation in different activities of the alliance" before making a decision on whether to join.
In Indonesia, the foreign ministry said it too had not yet decided whether to join.
"The government is still observing and waiting to see the modalities of the military coalition formed by Saudi Arabia," foreign ministry spokesman Arrmanatha Nasir told The Jakarta Post.
Malaysian Defence Minister Hishammuddin Hussein went further - expressing support for the coalition but ruling out any military involvement from Kuala Lumpur.
"The Saudi initiative does not involve any military commitment, but an understanding that we will combat militancy," he said.