Following PMQs, Sir Keir held the first of two days of meetings with the French president at Downing Street.
No new deal was reached, but Sir Keir and Macron agreed “a new deterrent” was needed to stop small boats, a readout of the meeting said.
Both leaders agreed stopping small boat crossings was “a shared priority” and vowed to push to “go further and make progress on new and innovative solutions,” Downing Street said.
By the end of the week, the prime minister is hoping to announce a new agreement, potentially including a “one in, one out” migrants return policy with France.
The arrangement would allow Britain to return migrants who arrive by small boat to France in exchange for accepting asylum seekers with a family connection in the UK.
A group of five Mediterranean countries have written to the European Commission about the issue, complaining they may be forced to accept people deported from the UK.
Sir Keir has also been pushing for France to revise its rules to allow police to intervene when boats are in shallow water, rather than requiring them still to be on land.
Last week the BBC witnessed French officers use a knife to puncture an inflatable boat after it had launched in an apparent change of tactics.