The midfielder, who has started the previous 12 league games for The Hatters was replaced by Luke Berry after just 32 minutes.
“It’s a slight hamstring and we’re just very cautious in terms of getting him off the pitch," Harford told Dunstable Today.
“We don’t want him to do any more damage as Macca’s very important to us. We had a few chats with a few of the players, ‘how are you feeling? Are you stiff? Are you ready to play?
“You look at Macca, he’s done his hamstring, he’s never done his hamstring before, it’s normally his calf. So that’s a new injury to Macca and Macca was up to play.
“Overall I like continuity, I like the players to get in a rhythm. I think they are in rhythm at the moment and that’s why I picked the same team.”
Elias Sorensen's nightmare loan spell at Blackpool has come to an abrupt end after being recalled by his parent club Newcastle United.
The Denmark under-21s striker earned a move to League One side in January after hitting 19 goals in a prolific season for the Magpies' youngsters.
However, matters failed to go to plan as the 19-year-old made just one appearance for the club - a cameo off the bench which lasted just 32 minutes against Wycombe Wanderers.
Sorensen hasn't featured in the Pool's squad for the last six games, finding himself behind Armand Gnanduillet, Chris Long and Joe Dodoo in the pecking order.
Meanwhile, Newcastle have also recalled Jamie Sterry and Cal Roberts, who were at Crewe Alexandra and Colchester United respectively.
Portsmouth manager Kenny Jackett has reassured January signing Lloyd Isgrove will get his chance to impress.
Isgrove, signed on loan from Barnsley until the end of the season, hasn't played a single League One minute since his move to the south coast.
A freak injury to Ronan Curtis where a gust of wind led to this finger being chopped off on Monday - which requires plastic surgery - Isgrove could soon feature in Jackett's starting XI.
You can read what Jackett told the Portsmouth News HERE.
In League Two, Mansfield Town chairman John Radford has completed the purchase of the One Call Stadium.
Radford, who bought the Stags in 2010, has been involved in a lengthy dispute about the ownership of the ground with Keith Haslam, one of the League Two club's previous owners.
However, a deal was agreed to buy the club's Field Mill site and the final payment has now been made. He said: "This is great news for me and the club."
"When I did the deal with Keith I looked forward to this day and being able to announce that we were completely in control of our own destiny as regards the One Call Stadium."