Trump's comments came shortly before Republican senators were set to begin a lunch where they are expected to decide whether to proceed with a vote on the Graham-Cassidy bill, despite expectations it would fail.
"We are disappointed in certain so-called Republicans."
But Trump also promised: "At some point there will be a repeal-and-replace" bill that he could sign into law.
Republicans hold 52 seats in the 100-member Senate and would need at least 50 GOP senators to vote for the bill for it to pass, assuming a tie-breaking vote from Vice President Mike Pence.
The deadline for passing the bill is Saturday.
After that, the budget reconciliation measure being used to fast-track the bill — and pass it with only a simple majority instead of the normal 60-vote minimum — will expire.
Monday's announcement by Collins that she would be the third GOP senator to buck party leaders on the bill was just the latest in a series of embarrassing failures by Republican leaders in their efforts to pass Obamacare repeal legislation.
It would be unusual for Senate Majority Leader Mitch McConnell, R-Ky., to hold a vote on a bill that his party was backing but is fated to lose.
However, it is possible that some GOP senators who support the bill will want the opportunity to publicly vote "yes" on the legislation to show constituents their commitment to repeal.
Murkowski, whose vote against a prior Obamacare repeal bill in July helped kill it, would not say how she would vote on Graham-Cassidy if a vote occurred.
Collins' announcement that she would oppose the bill came right after the Congressional Budget Office said that Graham-Cassidy, if it became law, would lead to millions more people who currently have health insurance becoming uninsured.
The CBO also said that the bill would slash spending on Medicaid — the joint federal-state program that offers health coverage to primarily poor people — by a whopping $1 trillion.
"The CBO's analysis on the earlier version of the bill, incomplete though it is due to time constraints, confirms that this bill will have a substantially negative impact on the number of people covered by insurance," Collins said Monday.